Composition for forming photosensitive dielectric material, and transfer film, dielectric material and electronic parts using the same

ABSTRACT

A photosensitive composition for forming a dielectric of the present invention comprising inorganic particles, an alkali developable resin and additives, wherein the additives comprise a compound having a quinonediazido group (C1), a compound containing at least two alkyletherified amino groups in the molecule (C2) and a thermal acid generator (C3), or wherein the inorganic particles comprise inorganic superfine particles (A-I) having a mean particle diameter of less than 0.05 μm and inorganic fine particles (A-II) having a mean particle diameter of not less than 0.05 μm.  
     The composition can be calcined at low temperatures to form a dielectric layer with high dimensional precision, said layer having a high dielectric constant and a low dielectric loss. Also provided are a dielectric and an electronic part prepared from the composition.

FIELD OF THE INVENTION

[0001] The present invention relates to a photosensitive composition forforming a dielectric, the composition being suitably employable to forma pattern with high dimensional precision; a transfer film obtained byapplying the photosensitive composition onto a substrate film; and adielectric and electronic parts prepared from the composition or thetransfer film.

BACKGROUND OF THE INVENTION

[0002] It is now a known technology to incorporate a high-dielectriclayer into a multilayer printed circuit board etc. to obtain a functionof condenser or the like. The high-dielectric layer can be prepared by,for example, adding inorganic powder of high dielectric constant to asolution obtained by dissolving a thermosetting resin in an organicsolvent; impregnating a fibrous reinforcing material such as glass fiberwith the solution to make up for the brittleness of the thermosettingresin; and calcining the impregnated material to evaporate the solventand cure the resin. However, it has been difficult with suchconventional methods to obtain a dielectric layer which has a highdielectric constant, generally 20 or more, and which is at the same timethin and has a low leakage current.

[0003] Further, various inorganic powders have been used in attempts toobtain a dielectric layer of a high dielectric constant. For example, ithas been found that a dielectric layer having a high dielectric constantcan be prepared by addition of an inorganic powder, such as of Fe₃O₄ ora mixture of ZnO and carbon, into polystyrene. However, dielectriclayers thus obtained, although high in dielectric constant, have a highdielectric loss so that they generate high heat in an alternatingelectric field. This heat generation causes deterioration of multilayerprinted circuit boards etc. including the dielectric film, and furthergives rise to troubles such as breakage of joint by thermal stress.Accordingly, there have been problems of poor reliability and durabilityof the semiconductor boards.

[0004] On the other hand, it is a known method for achieving a highdielectric constant to form a dielectric layer by calcining an inorganicpowder of high dielectric constant at high temperatures. However, due tothe calcination which should be carried out at high temperatures around1000° C., this method cannot be applied to uses where a dielectric layeris to be incorporated in a wiring board carrying electronic parts. Thus,it has been impossible to apply this method to versatile uses in theproduction of various kinds of semiconductor boards.

[0005] A screen printing process is a known method for formingdielectric layers. This screen printing process has been unable to dealwith difficult demands for accurate pattern position that come from therecent trends of boards toward large size and meticulous structure.

[0006] Accordingly, there has been a demand for a photosensitivecomposition for forming a dielectric which can be calcined at lowtemperatures to form a dielectric layer that has a high dielectricconstant and a low dielectric loss and is patterned with highdimensional precision.

OBJECT OF THE INVENTION

[0007] The present invention has been made in order to solve the aboveproblems related to the prior art. Accordingly, it is an object of theinvention to provide a photosensitive composition for forming adielectric which can be calcined at low temperatures to give adielectric layer that has a high dielectric constant and a lowdielectric loss and is patterned with high dimensional precision. It isa further object of the invention to provide a photosensitive transferfilm having a layer of the above composition, a dielectric prepared fromthe composition or the transfer film, and electronic parts including thedielectric.

DISCLOSURE OF THE INVENTION

[0008] As a result of an earnest study dedicated to solving the aboveproblems, the present inventors have found that a photosensitivecomposition for forming a dielectric or a photosensitive transfer filmcan be calcined at low temperatures not higher than 500° C. to give adielectric layer that has a high dielectric constant, a low dielectricloss and a low leakage current in spite of small thickness and furtherwhich can be patterned with high dimensional precision. Thephotosensitive composition comprises inorganic particles, analkali-soluble resin and an additive(s), the additive(s) is a specifickind(s) or the inorganic particles have a specific mean particlediameter. The photosensitive transfer film is coated with the abovecomposition. The invention has been completed based on these findings.

[0009] A first photosensitive composition for forming a dielectricaccording to the invention comprises (A) inorganic particles, (B) analkali developable resin, and (C) additives, wherein:

[0010] the alkali developable resin (B) comprises an alkali solubleresin having a phenolic hydroxyl group (B1); and

[0011] the additives (C) comprise a compound having a quinonediazidogroup (C1), a compound containing at least two alkyletherified aminogroups in the molecule (C2) and a thermal acid generator (C3).

[0012] In the first photosensitive composition,

[0013] the alkali developable resin (B) comprises preferably an alkalisoluble resin having a phenolic hydroxyl group (B1), and

[0014] the additives (C) comprise preferably a compound having aquinonediazido group (C1), a compound containing at least twoalkyletherified amino groups in the molecule (C2), a thermal acidgenerator (C3) and crosslinked fine particles (C4).

[0015] Preferably, the crosslinked fine particles (C4) have a meanparticle diameter of 30 to 500 nm.

[0016] A second photosensitive composition for forming a dielectriccomprises (A) inorganic particles, (B) an alkali developable resin, and(C) an additive, wherein:

[0017] the inorganic particles (A) comprise inorganic superfineparticles (A-I) having a mean particle diameter of less than 0.05 μm andinorganic fine particles (A-II) having a mean particle diameter of notless than 0.05 μm; and

[0018] the additive (C) comprises a photoacid generator (C5).

[0019] Preferably, the inorganic particles (A) are contained at 20 to95% by mass, the alkali developable resin (B) is contained at 1 to 60%by mass and the photoacid generator (C5) is contained at 0.1 to 30% bymass.

[0020] In the second photosensitive composition,

[0021] the alkali developable resin (B) is preferably at least one resinselected from the group consisting of a (meth)acrylic resin, ahydroxystyrene resin, a novolak resin, a polyester resin, a polyimideresin, a nylon resin and a polyetherimide resin.

[0022] A third photosensitive composition for forming a dielectriccomprises (A) inorganic particles, (B) an alkali developable resin, and(C) additives, wherein:

[0023] the inorganic particles (A) comprise inorganic superfineparticles (A-I) having a mean particle diameter of less than 0.05 μm andinorganic fine particles (A-II) having a mean particle diameter of notless than 0.05 μm;

[0024] the alkali developable resin (B) comprises an alkali solubleresin (B2); and

[0025] the additives (C) comprise a compound having an ethylenicallyunsaturated group (C6) and a photopolymerization initiator (C7).

[0026] Preferably, the inorganic particles (A) are contained at 20 to95% by mass, the alkali soluble resin (B2) is contained at 1 to 60% bymass, the compound having an ethylenically unsaturated group (C6) iscontained at 0.1 to 30% by mass, and the photopolymerization initiator(C7) is contained at 0.1 to 20% by mass.

[0027] The alkali soluble resin (B2) is preferably a resin selected fromthe group consisting of a (meth)acrylic resin, a hydroxystyrene resin, anovolak resin and a polyester resin. The compound having anethylenically unsaturated group (C6) is preferably a (meth)acrylatecompound, and is preferably contained at 20 to 500 parts by mass basedon 100 parts by mass of the alkali soluble resin (B2).

[0028] In the second or third photosensitive composition, the inorganicsuperfine particles (A-I) are preferably contained at 1 to 30 parts bymass and the inorganic fine particles (A-II) are contained at 99 to 70parts by mass on the basis of 100 parts by mass of the inorganicparticles (A). The inorganic particles (A) preferably comprise atitanium-containing metal oxide.

[0029] Preferably, the second or third photosensitive composition iscapable of forming a dielectric by heating at 500° C. or below, saiddielectric having a dielectric constant of not less than 20 and adielectric loss tangent of not more than 0.1.

[0030] A photosensitive transfer film according to the invention is asubstrate film and a layer of a photosensitive composition for forming adielectric comprising inorganic particles (A), an alkali developableresin (B) and an additive (C), said layer being provided in a thicknessof 1 to 100 μm on the substrate film, wherein:

[0031] the inorganic particles (A) comprise inorganic superfineparticles (A-I) having a mean particle diameter of less than 0.05 μm andinorganic fine particles (A-II) having a mean particle diameter of notless than 0.05 μm; and

[0032] the additive (C) comprises a photoacid generator (C5).

[0033] Preferably, the photosensitive transfer film is capable offorming a dielectric by heating at 500° C. or below, said dielectrichaving a dielectric constant of not less than 20 and a dielectric losstangent of not more than 0.1.

[0034] In the photosensitive transfer film, the inorganic particles (A)preferably comprise a titanium-containing metal oxide, and the alkalidevelopable resin (B) is preferably a resin selected from the groupconsisting of a (meth)acrylic resin, a hydroxystyrene resin, a novolakresin, a polyester resin, a polyimide resin, a nylon resin and apolyetherimide resin.

[0035] A dielectric according to the invention is prepared from any ofthe first to third photosensitive compositions. Preferably, thedielectric is prepared by heating the second or third photosensitivecomposition at 500° C. or below to cure the same, and has a dielectricconstant of not less than 20 and a dielectric loss tangent of not morethan 0.1. Also preferably, the dielectric is formed with use of thephotosensitive transfer film.

[0036] The dielectric may be a dielectric with a conductive foil, inwhich a dielectric obtained from the second photosensitive compositionor from the photosensitive transfer film is formed on the conductivefoil.

[0037] An electronic part according to the invention include thedielectric.

PREFERRED EMBODIMENTS OF THE INVENTION

[0038] The detailed description of the invention will begin withexplanation of the photosensitive compositions for forming a dielectric.

[0039] The photosensitive compositions can be prepared by kneadinginorganic particles (A), an alkali developable resin (B) and anadditive(s) (C) by use of a kneader such as a roll mill, a mixer, ahomomixer, a ball mill or a bead mill.

[0040] <First Photosensitive Composition For Forming Dielectric>

[0041] The first photosensitive composition for forming a dielectriccomprises:

[0042] (A) inorganic particles;

[0043] (B) an alkali developable resin which is an alkali soluble resinhaving a phenolic hydroxyl group (B1);

[0044] (C) additives which are a compound having a quinonediazido group(C1), a compound containing at least two alkyletherified amino groups inthe molecule (C2) and a thermal acid generator (C3); and optionally

[0045] (C4) crosslinked fine particles and

[0046] (D) a solvent.

[0047] When necessary, this first photosensitive composition may containanother additive (E) such as an epoxy compound, an adhesion auxiliary ora leveling agent.

[0048] The first photosensitive composition thus prepared is in pasteform with a fluidity sufficient for coating applications. Ideally, theviscosity thereof ranges from 10 to 50,000 mPa·s, and preferably from 20to 10,000 mPa·s.

[0049] Hereinafter, each component of the first photosensitivecomposition will be descried.

[0050] (A) Inorganic Particles:

[0051] The inorganic particles (A) used in the first photosensitivecomposition desirably have a dielectric constant of not less than 30,preferably not less than 50, and more preferably not less than 70. Theupper limit of the dielectric constant is not particularly limited. Thatis, there is no problem even if the dielectric constant is as high as30,000.

[0052] The inorganic particles (A) are preferably particles of a metaloxide, particularly those of a titanium-containing metal oxide. The“titanium-containing metal oxide” used herein refers to a compound thatcontains titanium and oxygen as essential elements. Preferred examplesof the titanium-containing metal oxide include a titanium-containingmonometal oxide which contains titanium as the only metallic element toform a crystalline structure or a titanium-containing compound oxidewhich contains titanium and another metallic element.

[0053] Exemplary titanium-containing monometal oxides include titaniumdioxide-based compounds, which will have an anatase structure or arutile structure.

[0054] Exemplary titanium-containing compound oxides include bariumtitanate-based, lead titanate-based, strontium titanate-based, bismuthtitanate-based, magnesium titanate-based, neodymium titanate-based andcalcium titanate-based compound oxides.

[0055] The “titanium dioxide-based compound” is defined as a compoundformed from titanium dioxide alone or from titanium dioxide and a minoradditive. This compound retains a crystalline structure of its principalcomponent, titanium dioxide. These definitions apply to other monometaloxides.

[0056] The “titanium-containing compound oxide” means a compound oxidewhich is formed from a titanium-containing monometal oxide and at leastone different metal oxide. The complex oxide is free of oxo-ionstructural units.

[0057] For the titanium-containing metal oxide for making up theinorganic particles (A) of the first photosensitive composition, atitanium dioxide-based compound with a rutile structure and bariumtitanate are preferred among the titanium monometal oxide and thetitanium-containing compound oxide, respectively.

[0058] Of these, barium titanate can be particularly preferably used.

[0059] The inorganic particles preferably have a mean particle diameterof 0.005 to 2.0 μm, more preferably 0.02 to 1.0 μm, still preferably0.02 to 0.8 μm, and particularly preferably 0.02 to 0.3 μm. Further, theinorganic particles preferably have a Dw/Dn ratio (Dw: weight-averageparticle diameter, Dn: number-average particle diameter) of not lessthan 1.05, more preferably not less than 1.1, still preferably not lessthan 1.2, and particularly preferably not less than 1.25. With the Dw/Dnratio being less than 1.05, those dielectric particles will have a lowpacking density when a dielectric layer is formed thin so that theleakage current may increase.

[0060] The inorganic particles (A) used in the first photosensitivecomposition may be in the shape of, although not particularly limitedto, sphere, granule, plate, scale, whisker, bar or filament. Of theseshapes, the inorganic particles preferably have a spherical, granular,plate or scale shape. The inorganic particles (A) in the above shapesmay be used either singly or in combination of two or more kinds.

[0061] The inorganic particles (A) to be used in the firstphotosensitive composition may be synthesized by, for example, a gasphase process, a sol-gel process or an RF plasma process. when theinorganic particles have been synthesized by a gas phase process, theycan be dispersed in a solvent by means of a conventional dispersingmeans with combined use of a dispersant, a bead mill, a kneader or ahigh-pressure homogenizer to be disrupted into primary particles.

[0062] Preferably, the first photosensitive composition contains theinorganic particles (A) at 20 to 85% by mass, more preferably 30 to 85%by mass, and still preferably 40 to 85% by mass based on 100% by mass ofthe total amount of the components (A), (B1), (C1), (C2), (C3) and (C4).

[0063] (B1) Alkali Soluble Resin Containing Phenolic Hydroxyl Group:

[0064] The alkali soluble resin having a phenolic hydroxyl group (B1)(hereinafter referred to as the “phenolic resin (B1)”) for use in thisfirst photosensitive composition is preferably a novólak resin but isnot particularly limited thereto. The novolak resin can be obtained bycondensing a phenol and an aldehyde in the presence of a catalyst.

[0065] Examples of the phenol used herein include phenol, o-cresol,m-cresol, p-cresol, o-ethylphenol, m-ethylphenol, p-ethylphenol,o-butylphenol, m-butylphenol, p-butylphenol, 2,3-xylenol, 2,4-xylenol,2,5-xylenol, 2,6-xylenol, 3,4-xylenol, 3,5-xylenol,2,3,5-trimethylphenol, 3,4,5-trimethylphenol, catechol, resorcinol,pyrogallol, α-naphthol and β-naphthol.

[0066] Examples of the aldehyde include formaldehyde, paraformaldehyde,acetaldehyde and benzaldehyde.

[0067] Exemplary novolak resins obtainable from these includephenol/formaldehyde condensate novolak resins, cresol/formaldehydecondensate novolak resins and phenol-naphthol/formaldehyde condensatenovolak resins.

[0068] Exemplary phenolic resins (B1) other than the novolak resinsinclude polyhydroxystyrene, copolymers thereof, phenol/xylyleneglycolcondensate resins, cresol/xylyleneglycol condensate resins andphenol/dicyclopentadiene condensate resins.

[0069] In the first photosensitive composition, a phenoliclow-molecular-weight compound (hereinafter the “phenolic compound (b1)”)other than the above phenolic resin (B1) may be used together with thephenolic resin (B1). Exemplary phenolic compounds include4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenylether,tris(4-hydroxyphenyl)methane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane,tris(4-hydroxyphenyl)ethane,1,3-bis[1-(4-hydroxyphenyl)-1-methylethyl]benzene,1,4-bis[1-(4-hydroxyphenyl)-1-methylethyl]benzene,4,6-bis[1-(4-hydroxyphenyl)-1-methylethyl]-1,3-dihydroxybenzene,1,1-bis(4-hydroxyphenyl)-1-[4-{1-(4-hydroxyphenyl)-1-methylethyl}phenyl]ethane,and 1,1,2,2-tetra(4-hydroxyphenyl)ethane. Preferably, the phenoliccompound (b1) is contained at 0 to 40% by mass, more preferably 0 to 30%by mass, and particularly preferably 1 to 20% by mass based on the totalamount of the phenolic resin (B1) and the phenolic compound (b1).

[0070] It is necessary that the phenolic resin (B1) have a mass-averagemolecular weight of at least 2,000, particularly from 2,000 to about20,000, in consideration of resolution, thermal shock properties andheat resistance of the resulting dielectric layer.

[0071] The first photosensitive composition contains the phenolic resin(B1) (and the phenolic compound (b1) when it is used in combination) at10 to 50% by mass, and preferably 13 to 45% by mass of the total amountof the components (A), (B1), (b1), (C1), (C2), (C3) and (C4). When thecomposition contains the phenolic resin (B1) in the above proportion,the dielectric layer formed from the composition can exhibit asufficient developability by an alkaline aqueous solution.

[0072] (C1) Compound Having Quinonediazido Group:

[0073] The compound having a quinonediazido group (C1) (hereinafterreferred to as the “quinonediazide compound (C1)”) used in the firstphotosensitive composition is an ester formed between either1,2-naphthoquinonediazido-4-sulfonic acid or1,2-naphthoquinonediazido-5-sulfonic acid and a compound having at leastone phenolic hydroxyl group. The compound having at least one phenolichydroxyl group is not particularly limited; preferably it has astructure represented by any of the following formulae:

[0074] wherein X₁ to X₁₀ independently denote a hydrogen atom, an alkylgroup of 1 to 4 carbon atoms, an alkoxy group 1 to 4 carbon atoms or ahydroxyl group provided, however, that at least one of X₁ to X₅ is ahydroxyl group; and A is a single bond, O, S, CH₂, C(CH₃)₂, C(CF₃)₂, C═Oor SO₂;

[0075] wherein X₁₁ to X₂₄, which may be the same or different, are thesame definition as X₁ to X₁₀ provided, however, that least one of X₁₁ toX₁₅ is a hydroxyl group; and R₁ to R₄ independently denote a hydrogenatom or an alkyl group 1 to 4 carbon atoms;

[0076] wherein X₂₅ to X₃₉, which may be the same or different, are thesame definition as X₁ to X₁₀ provided, however, that at least one of X₂₅to X₂₉ is a hydroxyl group and that at least one of X₃₀ to X₃₄ is ahydroxyl group; and R₅ denotes a hydrogen atom or an alkyl group 1 to 4carbon atoms;

[0077] wherein X₄₀ to X₅₈, which may be the same or different, are thesame definition as X₁ to X₁₀ provided, however, that at least one of X₄₀to X₄₄ is a hydroxyl group, that at least one of X₄₅ to X₄₉ is ahydroxyl group and that at least one of X₅₀ to X₅₄ is a hydroxyl group;and R₆ to R₈ independently denote a hydrogen atom or an alkyl group 1 to4 carbon atoms;

[0078] wherein X₅₉ to X₇₂, which may be the same or different, are thesame definition as X₁ to X₁₀ provided, however, that at least one of X₅₉to X₆₂ is a hydroxyl group and that at least one of X₆₃ to X₆₇ is ahydroxyl group.

[0079] Examples of the quinonediazide compound (C1) include esters ofeither 1,2-naphthoquinonediazido-4-sulfonic acid or1,2-naphthoquinonediazido-5-sulfonic acid with any of4,4′-dihydroxydiphenylmethane, 4,4′-dihydroxydiphenylether,2,3,4-trihydroxybenzophenone, 2,3,4,4′-tetrahydroxybenzophenone,2,3,4,2′,4′-pentahydroxybenzophenone, tris(4-hydroxyphenyl)methane,tris(4-hydroxyphenyl)ethane, 1,1-bis(4-hydroxyphenyl)-1-phenylethane,1,3-bis[1-(4-hydroxyphenyl)-1-methylethyl]benzene,1,4-bis[1-(4-hydroxyphenyl)-1-methylethyl]benzene,4,6-bis[1-(4-hydroxyphenyl)-1-methylethyl]-1,3-dihydroxybenzene, and1,1-bis(4-hydroxyphenyl)-1-[4-{1-(4-hydroxyphenyl)-1-methylethyl}phenyl]ethane.

[0080] Desirably, the first photosensitive composition contains thequinonediazide compound (C1) at 10 to 50 parts by mass, and preferably15 to 30 parts by mass based on 100 parts by mass of the phenolic resin(B1) (or the total amount of the phenolic resin (B1) and the phenoliccompound (b1) when they are used in combination). When the proportion ofthe quinonediazide compound (C1) falls below the lower limit, theretention percentage of layer in non-photoexposed areas may be loweredand the image may not be obtained accurately as designed with a patternmask. When the proportion of the quinonediazide compound (C1) exceedsthe upper limit, the pattern may be deteriorated and the composition mayfoam during the curing process.

[0081] (C2) Compound Containing At Least Two Alkyletherified AminoGroups In Molecule (Curing Agent):

[0082] The compound containing at least two alkyletherified amino groupsin the molecule (C2) (hereinafter referred to as the “curing agent(C2)”) used in the first composition works as a crosslinking agent(curing agent) which reacts with the phenolic resin (B1). Examples ofthe curing agent (C2) include nitrogen-containing compounds, such as(poly)methylolated melamine, (poly)methylolated glycoluril,(poly)methylolated benzoguanamine and (poly)methylolated urea, in whichall or part of active methylol groups have been alkyletherified.Exemplary alkyl groups include methyl, ethyl, butyl and mixturesthereof. The curing agent may contain an oligomer component resultingfrom partial self-condensation of the nitrogen-containing compound.Examples of such curing agents include hexamethoxymethylated melamine,hexabutoxymethylated melamine, tetramethoxymethylated glycoluril andtetrabutoxymethylated glycoluril. These curing agents (C2) may be usedeither singly or in combination of two or more kinds.

[0083] Desirably, the first photosensitive composition contains thecuring agent (C2) at 1 to 100 parts by weight, and preferably 5 to 50parts by weight based on 100 parts by weight of the phenolic resin (B1)(or the total amount of the phenolic resin (B1) and the phenoliccompound (b1) when they are used in combination). When the proportion ofthe curing agent (C2) falls below the lower limit, the curing cannot beeffected sufficiently to result in lowered dielectric properties of thecured product. Whereas the proportion over the upper limit may lead todeteriorated patterning properties or heat resistance.

[0084] (C3) Thermal Acid Generator:

[0085] The thermal acid generator (C3) (hereinafter referred to as the“acid generator (C3)”) used in the first composition may be any compoundthat generates an acid when heated at appropriate temperatures, e.g. at50 to 250° C. Examples thereof include, but not limited thereto,sulfonium salts, diazonium salts, halogen-containing compounds andsulfonate compounds. The generated acid works as a catalyst toaccelerate the reaction between the alkylether groups in the curingagent (C2) and the phenolic resin (B1).

[0086] Examples of the acid generator (C3) includebenzylmethylphenylsulfonium hexafluoroantimonate,benzylmethylphenylsulfonium hexafluorophosphate,benzylmethylphenylsulfonium tetrafluoroborate,benzylmethylphenylsulfonium trifluoromethanesulfonate,benzyl(4-hydroxyphenyl)methylsulfonium hexafluoroantimonate,benzyl(4-hydroxyphenyl)methylsulfonium hexafluorophosphate,benzyl(4-hydroxyphenyl)methylsulfonium tetrafluoroborate,benzyl(4-hydroxyphenyl)methylsulfonium trifluoromethanesulfonate,benzenediazonium hexafluoroantimonate, benzenediazoniumhexafluorophosphate, benzenediazonium tetrafluoroborate,benzenediazonium trifluoromethanesulfonate, naphthalenediazoniumhexafluoroantimonate, and naphthalenediazoniumtrifluoromethanesulfonate.

[0087] Desirably, the first photosensitive composition contains the acidgenerator (C3) at 0.1 to 10 parts by weight, and preferably 0.5 to 5parts by weight based on 100 parts by weight of the phenolic resin (B1)(or the total amount of the phenolic resin (B1) and the phenoliccompound (b1) when they are used in combination). When the proportion ofthe acid generator (C3) falls below the lower limit, the resultant curedproduct may have poor solvent resistance. Whereas the proportion overthe upper limit may result in lowering of electrical insulatingproperties.

[0088] (C4) Crosslinked Fine Particles:

[0089] The crosslinked fine particles (C4) to be used in the firstcomposition may be any particles provided that the polymer making up theparticles has Tg of not higher than 0° C. Preferably, the crosslinkedfine particles are obtained by copolymerizing a crosslinkable monomer(hereinafter referred to as the “crosslinkable monomer”) which has atleast two unsaturated polymerizable groups with one or more differentmonomers (hereinafter referred to as the “different monomer(s)”) whichis selected so that the resultant copolymer for making up thecrosslinked fine particles (C4) has Tg of not higher than 0° C.Preferably, the different monomer has a functional group other thanpolymerizable groups, such as a carboxyl, epoxy, amino, isocyanate orhydroxyl group, and is such that the resulting copolymer for making upthe crosslinked fine particles (C4) has Tg of not higher than 0° C.

[0090] Exemplary crosslinkable monomers include compounds with pluralpolymerizable unsaturated groups, such as divinylbenzene, diallylphthalate, ethylene glycol di(meth)acrylate, propylene glycoldi(meth)acrylate, trimethylolpropane tri(meth)acrylate, pentaerythritoltri(meth)acrylate, polyethylene glycol di(meth)acrylate andpolypropylene glycol di(meth)acrylate. On these, divinylbenzene ispreferable.

[0091] In preparing the crosslinked fine particles (C4) for use in thefirst composition, the crosslinkable monomer is preferably used at 1 to20% by weight, and more preferably 2 to 10% by weight based on the totalamount of all the monomers to be copolymerized.

[0092] Examples of the different monomers include:

[0093] diene compounds such as butadiene, isoprene, dimethylbutadiene,chloroprene and 1,3-pentadiene;

[0094] unsaturated nitrile compounds such as (meth)acrylonitrile,α-chloroacrylonitrile, α-chloromethylacrylonitrile,α-methoxyacrylonitrile, α-ethoxyacrylonitrile, nitrile crotonate,nitrile cinnamate, dinitrile itaconate, dinitrile maleate and dinitrilefumarate;

[0095] unsaturated amides such as (meth)acrylamide,N,N′-methylenebis(meth)acrylamide, N,N′-ethylenebis(meth)acrylamide,N,N′-hexamethylenebis(meth)acrylamide, N-hydroxymethyl(meth)acrylamide,N-(2-hydroxyethyl)(meth)acrylamide,N,N-bis(2-hydroxyethyl)(meth)acrylamide, crotonic amide and cinnamicamide;

[0096] (meth)acrylates such as methyl (meth)acrylate, ethyl(meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, hexyl(meth)acrylate, lauryl (meth)acrylate, polyethylene glycol(meth)acrylate and polypropylene glycol (meth)acrylate;

[0097] aromatic vinyl compounds such as styrene, α-methylstyrene,o-methoxystyrene, p-hydroxystyrene and p-isopropenylphenol;

[0098] epoxy (meth)acrylates resulting from the reaction of diglycidylether of bisphenol A, diglycidyl ether of glycol, etc. with(meth)acrylic acid, hydroxyalkyl (meth)acrylate, etc.; and urethane(meth)acrylates resulting from the reaction of hydroxyalkyl(meth)acrylate with polyisocyanate;

[0099] unsaturated compounds having an epoxy group such as glycidyl(meth)acrylate and (meth)allyl glycidyl ether;

[0100] unsaturated acid compounds such as (meth)acrylic acid, itaconicacid, β-(meth)acryloxyethyl succinate, β-(meth)acryloxyethyl maleate,β-(meth)acryloxyethyl phthalate and β-(meth)acryloxyethylhexahydrophthalate;

[0101] unsaturated compounds having an amino group such as dimethylamino(meth)acrylate and diethylamino (meth)acrylate;

[0102] unsaturated compounds having an amido group such as(meth)acrylamide and dimethyl (meth)acrylamide; and

[0103] unsaturated compounds having a hydroxyl group such ashydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate andhydroxybutyl (meth)acrylate.

[0104] Of these different monomers, butadiene, isoprene,(meth)acrylonitrile, alkyl (meth)acrylates, styrene, p-hydroxystyrene,p-isopropenylphenol, glycidyl (meth)acrylate, (meth)acrylic acid,hydroxyalkyl (meth)acrylates, etc. may be preferably used.

[0105] As the different monomer, at least one kind of diene compounds,particularly butadiene, is preferably used. Desirably, the dienecompound is used at 20 to 80% by weight, and preferably 30 to 70% byweight based on the total amount of all the monomers to becopolymerized.

[0106] The crosslinked fine particles (C4) for use in the firstcomposition can be obtained as rubber-like soft fine particles when thediene compound such as butadiene has been copolymerized in the aboveproportion based on the total amount of all the monomers. Further, theabove amount of the different monomer leads to excellent crackresistance and durability of the resulting cured layer.

[0107] Desirably, the crosslinked fine particles (C4) used in the firstcomposition have a mean particle diameter of 30 to 500 nm, preferably 40to 200 nm, and more preferably 50 to 120 nm. The particle diameters ofthe crosslinked fine particles (C4) may be controlled by any method. Thecontrol method is not limited to the above. In the case where theparticles (C4) are synthesized by emulsion polymerization, the particlediameters can be controlled by adjusting the amount of emulsifying agentto regulate the number of micells formed during the emulsionpolymerization.

[0108] Desirably, the crosslinked fine particles (C4) are used at 0 to50 parts by weight, preferably 1 to 50 parts by weight, and morepreferably 5 to 30 parts by weight based on 100 parts by weight of thephenolic resin (B1) (or the total amount of the phenolic resin (B1) andthe phenolic compound (b1) when they are used in combination). When theproportion of the crosslinked fine particles (C4) falls below the lowerlimit, the resultant cured layer may have poor thermal shock properties.Whereas the proportion over the upper limit may result in deteriorationof resolution and heat resistance of the cured layer; further it maycause lowering of compatibility and dispersion properties of theparticles with other components. Containment of the crosslinked fineparticles enables the photosensitive composition for forming adielectric to provide a cured layer that has improved thermal shockproperties.

[0109] (D) Solvent:

[0110] The solvent (D) is incorporated in the first composition toimprove handling properties or to control the viscosity or storagestability of the composition. Examples of the solvent (D) include, butnot particularly limited thereto:

[0111] ethylene glycol monoalkylether acetates such as ethylene glycolmonomethylether acetate and ethylene glycol monoethylether acetate;

[0112] propylene glycol monoalkylethers such as propylene glycolmonomethylether, propylene glycol monoethylether, propylene glycolmonopropylether and propylene glycol monobutylether;

[0113] propylene glycol dialkylethers such as propylene glycoldimethylether, propylene glycol diethylether, propylene glycoldipropylether and propylene glycol dibutylether;

[0114] propylene glycol monoalkylether acetates such as propylene glycolmonomethylether acetate, propylene glycol monoethylether acetate,propylene glycol monopropylether acetate and propylene glycolmonobutylether acetate;

[0115] cellosolves such as ethyl cellosolve and butyl cellosolve;

[0116] carbitols such as butyl carbitol;

[0117] lactates such as methyl lactate, ethyl lactate, n-propyl lactateand isopropyl lactate;

[0118] aliphatic carboxylates such as ethyl acetate, n-propyl acetate,isopropyl acetate, n-butyl acetate, isobutyl acetate, n-amyl acetate,isoamyl acetate, isopropyl propionate, n-butyl propionate and isobutylpropionate;

[0119] other esters such as methyl 3-methoxypropionate, ethyl3-methoxypropionate, methyl 3-ethoxypropionate, ethyl3-ethoxypropionate, methylpyruvate and ethyl pyruvate;

[0120] aromatic hydrocarbons such as toluene and xylene;

[0121] ketones such as 2-heptanone, 3-heptanone, 4-heptanone andcyclohexanone;

[0122] amides such as N-dimethylformamide, N-methylacetamide,N,N-dimethylacetamide and N-methylpyrrolidone; and

[0123] lactones such as γ-butyrolactone.

[0124] These solvents (D) may be used either singly or in combination oftwo or more kinds.

[0125] (E) Another Additive:

[0126] The first photosensitive composition may further contain anotheradditive (E), such as an epoxy compound, an adhesion auxiliary or aleveling agent. Examples of the epoxy compounds include novolak epoxyresins, bisphenol epoxy resins, alicyclic epoxy resins and aliphaticepoxy resins. These additives (E) may be used within limits notdetrimental to the characteristics of the composition.

[0127] <Second Photosensitive Composition For Forming Dielectric>

[0128] The second photosensitive composition for forming a dielectriccomprises:

[0129] (A) inorganic particles which comprise inorganic superfineparticles (A-I) having a mean particle diameter of less than 0.05 μm andinorganic fine particles (A-II) having a mean particle diameter of notless than 0.05 μm;

[0130] (B) an alkali developable resin;

[0131] (C) an additive which is a photoacid generator (C5); andoptionally

[0132] (D) a solvent and

[0133] (E) another additive.

[0134] The second photosensitive composition can be prepared by kneadingthese components with a kneader such as a roll mill, a mixer, ahomomixer, a ball mill or a bead mill.

[0135] This second composition prepared as above is in paste form with afluidity sufficient for coating applications. Ideally, the viscositythereof ranges from 10 to 100,000 mPa·s, and preferably from 50 to10,000 mPa·s. Also desirably, this second photosensitive composition iscapable of forming, upon heating at temperatures not higher than 500°C., a dielectric that has a dielectric constant of not less than 20 anda dielectric loss tangent of not more than 0.1.

[0136] Hereinafter, each component of the second photosensitivecomposition will be descried.

[0137] (A) Inorganic Particles:

[0138] The inorganic particles (A) for the second composition shouldcomprise inorganic superfine particles (A-I) having a mean particlediameter of less than 0.05 μm and inorganic fine particles (A-II) havinga mean particle diameter of not less than 0.05 μm. The inorganicparticles used herein may be those used in the first composition whenthe above conditions are satisfied.

[0139] To improve the dispersibility of the inorganic particles (A) inaqueous media, they may be suitably surface-treated with silica, aluminaor the like.

[0140] Desirably, the second photosensitive composition contains theinorganic superfine particles (A-I) at 1 to 30 parts by mass, andpreferably 5 to 20 parts by mass, and the inorganic fine particles(A-II) at 99 to 70 parts by mass, and preferably 95 to 80 parts by massbased on 100 parts by mass of the inorganic particles (A). The use ofthe above inorganic particles in the above proportion leads to a highpacking density of the particles so that the resulting dielectric canhave a high dielectric constant.

[0141] The mean particle diameter of the inorganic particles, i.e., thatof the whole of the inorganic superfine particles (A-I) and theinorganic fine particles (A-II), is preferably between 0.005 and 2.0 μm,more preferably 0.02 and 1.0 μm, still preferably 0.02 and 0.8 μm, andparticularly preferably 0.02 and 0.3 μm. Further, the Dw/Dn ratio (Dw:weight-average particle diameter, Dn: number-average particle diameter)is preferably not less than 1.05, more preferably not less than 1.1,still preferably not less than 1.2, and particularly preferably not lessthan 1.25. With the Dw/Dn ratio being less than 1.05, those dielectricparticles will have a low packing density when a dielectric layer isformed thin so that the leakage current may unfavorably increase.

[0142] In the second photosensitive composition, the amount of theinorganic particles (A) (total amount of superfine particles (A-I) andfine particles (A-II)) is preferably 20 to 95% by mass, preferably 40 to90% by mass, and more preferably 60 to 85% by mass on the basis of 100%by mass of the total amount of the components (A), (B) and (C5).

[0143] (B) Alkali Developable Resin:

[0144] The alkali developable resin (B) used in the second compositionhas an “alkali developability”, which is a property of being dissolvedby an alkaline developer. In other words, the alkali developability isunderstood as an alkali solubility whereby desired development can beaccomplished.

[0145] Various resins can be used as the alkali developable resin (B)and examples thereof include (meth)acrylic resins, hydroxystyreneresins, novolak resins, polyester resins, polyimide resins, nylon resinsand polyetherimide resins.

[0146] Of these alkali developable resins (B), (meth)acrylic resins arepreferable.

[0147] Particularly preferred examples thereof include:

[0148] copolymers comprising a monomer having a carboxyl group (b2)(hereinafter referred to as “monomer (b2)”) and another copolymerizablemonomer (b4) (hereinafter referred to as “monomer (b4)”); and

[0149] copolymers comprising a monomer (b2), a monomer having an epoxygroup (b3) (hereinafter referred to as “monomer (b3)”) and a monomer(b4).

[0150] Examples of the monomer (b2) (monomers having a carboxyl group)include acrylic acid, methacrylic acid, maleic acid, fumaric acid,crotonic acid, itaconic acid, citraconic acid, mesaconic acid, cinnamicacid, mono(2-(meth)acryloyloxyethyl) succinate andω-carboxypolycaprolactone mono(meth)acrylate.

[0151] Examples of the monomer (b3) (monomers having a epoxy group)include glycidyl acrylate, glycidyl methacrylate, glycidylα-ethylacrylate, glycidyl α-n-propylacrylate, glycidylα-n-butylacrylate, 3,4-epoxybutyl acrylate, 3,4-epoxybutyl methacrylate,6,7-epoxyheptyl acrylate, 6,7-epoxyheptyl methacrylate, 6,7-epoxyheptylα-ethylacrylate, N-[4-(2,3-epoxypropoxy)-3,5-dimethylbenzyl] acrylamideand N-[4-(2,3-epoxypropoxy)-3,5-dimethylphenylpropyl] acrylamide.

[0152] Examples of the monomer (b4) which is a copolymerizable monomerinclude:

[0153] methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl(meth)acrylate, n-lauryl (meth)acrylate, benzyl (meth)acrylate anddicyclopentanyl (meth)acrylate;

[0154] (meth)acrylates other than the monomers (b2) and (b3) (for thecopolymers comprising the monomer (b3));

[0155] aromatic vinyl monomers such as styrene and α-methylstyrene;

[0156] conjugated dienes such as butadiene and isoprene; and

[0157] macromonomers having a polymerizable unsaturated group, e.g., a(meth)acryloyl group, in one terminal of its polymer chain, such aspolystyrene, polymethyl (meth)acrylate, polyethyl (meth)acrylate andpolybenzyl (meth)acrylate.

[0158] Because of the presence of copolymerized components derived froma monomer having a carboxyl group of the monomers (b2) and/or (b3) or aphenolic hydroxyl group, the copolymers comprising the monomers (b2) and(b4) or those comprising the monomers (b2), (b3) and (b4) have thealkali solubility. In particular, the copolymers comprising the monomers(b2), (b3) and (b4) are preferable from the viewpoints of dispersionstability for the inorganic particles (A) and solubility by an alkalinedeveloper after-mentioned. Preferably, the copolymer contains componentunits derived from the monomer (b2) at 1 to 50% by mass, andparticularly preferably 5 to 30% by mass, and those derived from themonomer (b3) at 1 to 50% by mass, and particularly preferably 5 to 30%by mass, and those derived from the monomer (b4) at 1 to 98% by mass,and particularly preferably 40 to 90% by mass.

[0159] The alkali developable resin (B) in the second compositionpreferably has a mass-average molecular weight in terms of polystyreneas measured by GPC (hereinafter referred to as simply the “mass-averagemolecular weight (Mw)”) of 5,000 to 5,000,000, and more preferably10,000 to 300,000.

[0160] Desirably, the second photosensitive composition contains thealkali developable resin (B) at 1 to 500 parts by mass, preferably 10 to500 parts by mass, and more preferably 10 to 200 parts by mass based on100 parts by mass of the inorganic particles (A).

[0161] Also desirably, the content of the alkali developable resin (B)in the second composition is 1 to 60% by mass, preferably 2 to 40% bymass, and more preferably 5 to 30% by mass on the basis of 100% by massof the total amount of the components (A), (B) and (C5).

[0162] The second photosensitive composition may contain another resinthan the alkali developable resin, such as a bismaleimide resin or anepoxy resin.

[0163] (C5) Photoacid Generator:

[0164] The photoacid generator (C5) is a compound which generates anacid on exposure to radiation. Examples thereof include1,2-benzoquinonediazidosulfonic acid esters,1,2-naphthoquinonediazidosulfonic acid esters,1,2-benzoquinonediazidosulfonic acid amides and1,2-naphthoquinonediazidosulfonic acid amides. Specific examples includethe 1,2-quinonediazide compounds described in “Light-Sensitive Systems”by J. Kosar, pp. 339-352 (1965) John Wiley & Sons, Inc. (New York) and“Photoresist” by W. S. De Forest p. 50 (1975), McGraw-Hill, Inc. (NewYork).

[0165] Of the above compounds, those exhibiting excellentpost-irradiation transparency in the visible light range of 400 to 800nm are preferable; listed as examples are ester compounds of1,2-benzoquinonediazido-4-sulfonic acid,1,2-naphthoquinonediazido-4-sulfonic acid or1,2-naphthoquinonediazido-5-sulfonic acid with any of2,3,4-trihydroxybenzophenone, 2,3,4,4′-tetrahydroxybenzophenone,3′-methoxy-2,3,4,4′-tetrahydroxybenzophenone,2,2′,5,5′-tetramethyl-2′,4,4′-trihydroxytriphenylmethane,4,4′-[1-[4-(1-(4-hydroxyphenyl)-1-methylethyl)phenyl]ethylidene]diphenol and2,4,4-trimethyl-2′,4′,7-trihydroxy-2-phenylflavan.

[0166] The content of the photoacid generator (C5) is preferably 5 to100 parts by mass, and particularly preferably 10 to 50 parts by massbased on 100 parts by mass of the alkali developable resin (B). Thephotoacid generator (C5) in a content below this lower limit generatesan acid in too small amount upon absorption of radiation. Therefore, thesolubility for an alkaline aqueous solution will not change betweenbefore and after the composition has been exposed to radiation. Thiswill result in difficult patterning, and the pattern may have a problemin heat resistance. Whereas the photoacid generator added over the upperlimit will remain in a substantial amount if the composition is exposedto radiation only for a short time. Accordingly, the insolubility for analkaline aqueous solution will become too high and the development maybe difficult as a result.

[0167] Desirably, the second photosensitive composition contains thephotoacid generator (C5) at 0.1 to 30% by mass, preferably 0.5 to 20% bymass, and more preferably 1 to 10% by mass based on 100% by mass of thetotal amount of the components (A), (B) and (C5).

[0168] (D) Solvent:

[0169] The second photosensitive composition may optionally contain asolvent (D).

[0170] The solvent (D) preferably has the following properties:

[0171] it has a good affinity for the inorganic superfine particles(A-I) and the inorganic fine particles (A-II),

[0172] it has a good solubility for the alkali developable resin (B),the photoacid generator (C5) and an optional additive (E)after-mentioned,

[0173] it can impart an appropriate viscosity to the secondphotosensitive composition, and

[0174] it can be readily evaporated by drying.

[0175] Examples of the solvent (D) include:

[0176] ketones such as diethyl ketone, methyl butyl ketone, dipropylketone and cyclohexanone;

[0177] alcohols such as n-pentanol, 4-methyl-2-pentanol, cyclohexanoland diacetone alcohol;

[0178] ethereal alcohols such as ethylene glycol monomethyl ether,ethylene glycol monoethyl ether, ethylene glycol monobutyl ether,propylene glycol monomethyl ether and propylene glycol monoethyl ether;

[0179] alkyl esters of saturated aliphatic monocarboxylic acids such asn-butyl acetate and amyl acetate;

[0180] lactic acid esters such as ethyl lactate and n-butyl lactate; and

[0181] ether esters such as methyl cellosolve acetate, ethyl cellosolveacetate, propylene glycol monomethyl ether acetate and ethyl-3-ethoxypropionate.

[0182] These solvents may be used either singly or in combination of twoor more kinds.

[0183] The content of the solvent (D) in the second composition can beappropriately determined to obtain a good flowability. Desirably, it isin the range of 1 to 10,000 parts by mass, and preferably 10 to 1,000parts by mass based on 100 parts by mass of the inorganic particles (A).

[0184] (E) Another Additive:

[0185] In addition to the above components (A), (B) and (C5), the secondphotosensitive composition may optionally contain another additive (E).Exemplary additives (E) include a plasticizer, an adhesion auxiliary, adispersant, a filler, a storage stabilizer, an anti-foaming agent, anantioxidant, an ultraviolet light absorber, a leveling agent and adeveloping accelerator.

[0186] (i) Adhesion Auxiliary:

[0187] For use as the adhesion auxiliary, at least one coupling agentcan be selected from silane coupling agents, aluminum coupling agents,titanate coupling agents and zirconate coupling agents. Of these, silanecoupling agents such as a compound represented by the formula (6)((alkyl) alkoxysilanes having a saturated alkyl group), which canachieve sufficient adhesion in relatively small amounts, are preferablyused.

[0188] wherein p is an integer of 3 to 20, m is an integer of 1 to 3, nis an integer of 1 to 3, and a is an integer of 1 to 3.

[0189] The indicator p for carbon number in the saturated alkyl groupranges from 3 to 20, and preferably 4 to 16.

[0190] Examples of the silane coupling agents of the formula (6)include:

[0191] saturated alkyl dimethyl methoxy silanes (a=1, m=1, n=1) such asn-propyl dimethyl methoxy silane, n-butyl dimethyl methoxy silane,n-decyl dimethyl methoxy silane, n-hexadecyl dimethyl methoxy silane andN-eicosane dimethyl methoxy silane;

[0192] saturated alkyl diethyl methoxy silanes (a=1, m=1, n=2) such asn-propyl diethyl methoxy silane, n-butyl diethyl methoxy silane, n-decyldiethyl methoxy silane, n-hexadecyl diethyl methoxy silane andn-eicosane diethyl methoxy silane;

[0193] saturated alkyl dipropyl methoxy silanes (a=1, m=1, n=3) such asn-butyl dipropyl methoxy silane, n-decyl dipropyl methoxy silane,n-hexadecyl dipropyl methoxy silane and n-eicosane dipropyl methoxysilanes;

[0194] saturated alkyl dimethyl ethoxy silanes (a=1, m=2, n=1) such asn-propyl dimethyl ethoxy silane, n-butyl dimethyl ethoxy silane, n-decyldimethyl ethoxy silane, n-hexadecyl dimethyl ethoxy silane andn-eicosane dimethyl ethoxy silane;

[0195] saturated alkyl diethyl ethoxy silanes (a=1, m=2, n=2) such asn-propyl diethyl ethoxy silane, n-butyl diethyl ethoxy silane, n-decyldiethyl ethoxy silane, n-hexadecyl diethyl ethoxy silane and n-eicosanediethyl ethoxy silane;

[0196] saturated alkyl dipropyl ethoxy silanes (a=1, m=2, n=3) such asn-butyl dipropyl ethoxy silane, n-decyl dipropyl ethoxy silane,n-hexadecyl dipropyl ethoxy silane and n-eicosane dipropyl ethoxysilane;

[0197] saturated alkyl dimethyl propoxy silanes (a=1, m=3, n=1) such asn-propyl dimethyl propoxy silane, n-butyl dimethyl propoxy silane,n-decyl dimethyl propoxy silane, n-hexadecyl dimethyl propoxy silane andn-eicosane dimethyl propoxy silane;

[0198] saturated alkyl diethyl propoxy silanes (a=1, m=3, n=2) such asn-propyl diethyl propoxy silane, n-butyl diethyl propoxy silane, n-decyldiethyl propoxy silane, n-hexadecyl diethyl propoxy silane andn-eicosane diethyl propoxy silane;

[0199] saturated alkyl dipropyl propoxy silanes (a=1, m=3, n=3) such asn-butyl dipropyl propoxy silane, n-decyl dipropyl propoxy silane,n-hexadecyl dipropyl propoxy silane and n-eicosane dipropyl propoxysilane;

[0200] saturated alkyl methyl dimethoxy silanes (a=2, m=1, n=1) such asn-propyl methyl dimethoxy silane, n-butyl methyl dimethoxy silane,n-decyl methyl dimethoxy silane, n-hexadecyl methyl dimethoxy silane andn-eicosane methyl dimethoxy silane;

[0201] saturated alkyl ethyl dimethoxy silanes (a=2, m=1, n=2) such asn-propyl ethyl dimethoxy silane, n-butyl ethyl dimethoxy silane, n-decylethyl dimethoxy silane, n-hexadecyl ethyl dimethoxy silane andn-eicosane ethyl dimethoxy silane;

[0202] saturated alkyl propyl dimethoxy silanes (a=2, m=1, n=3) such asn-butyl propyl dimethoxy silane, n-decyl propyl dimethoxy silane,n-hexadecyl propyl dimethoxy silane and n-eicosane propyl dimethoxysilane;

[0203] saturated alkyl methyl diethoxy silanes (a=2, m=2, n=1) such asn-propyl methyl diethoxy silane, n-butyl methyl diethoxy silane, n-decylmethyl diethoxy silane, n-hexadecyl methyl diethoxy silane andn-eicosane methyl diethoxy silane;

[0204] saturated alkyl ethyl diethoxy silanes (a=2, m=2, n=2) such asn-propyl ethyl diethoxy silane, n-butyl ethyl diethoxy silane, n-decylethyl diethoxy silane, n-hexadecyl ethyl diethoxy silane and n-eicosaneethyl diethoxy silane;

[0205] saturated alkyl propyl diethoxy silanes (a=2, m=2, n=3) such asn-butyl propyl diethoxy silane, n-decyl propyl diethoxy silane,n-hexadecyl propyl diethoxy silane and n-eicosane propyl diethoxysilane;

[0206] saturated alkyl methyl dipropoxy silanes (a=2, m=3, n=1) such asn-propyl methyl dipropoxy silane, n-butyl methyl dipropoxy silane,n-decyl methyl dipropoxy silane, n-hexadecyl methyl dipropoxy silane andn-eicosane methyl dipropoxy silane;

[0207] saturated alkyl ethyl dipropoxy silanes (a=2, m=3, n=2) such asn-propyl ethyl dipropoxy silane, n-butyl ethyl dipropoxy silane, n-decylethyl dipropoxy silane, n-hexadecyl ethyl dipropoxy silane andn-eicosane ethyl dipropoxy silane;

[0208] saturated alkyl propyl dipropoxy silanes (a=2, m=3, n=3) such asn-butyl propyl dipropoxy silane, n-decyl propyl dipropoxy silane,n-hexadecyl propyl dipropoxy silane and n-eicosane propyl dipropoxysilane;

[0209] saturated alkyl trimethoxy silanes (a=3, m=1) such as n-propyltrimethoxy silane, n-butyl trimethoxy silane, n-decyl trimethoxy silane,n-hexadecyl trimethoxy silane and n-eicosane trimethoxy silane;

[0210] saturated alkyl triethoxy silanes (a=3, m=2) such as n-propyltriethoxy silane, n-butyl triethoxy silane, n-decyl triethoxy silane,n-hexadecyl triethoxy silane and n-eicosane triethoxy silane; and

[0211] saturated alkyl tripropoxy silanes (a=3, m=3) such as n-propyltripropoxy silane, n-butyl tripropoxy silane, n-decyl tripropoxy silane,n-hexadecyl tripropoxy silane and n-eicosane tripropoxy silane.

[0212] The above compounds may be used either singly or in combinationof two or more kinds.

[0213] Of these, particularly preferable are n-butyl trimethoxy silane,n-decyl trimethoxy silane, n-hexadecyl trimethoxy silane, n-decyldimethyl methoxy silane, n-hexadecyl dimethyl methoxy silane, n-butyltriethoxy silane, n-decyl triethoxy silane, n-hexadecyl triethoxysilane, n-decyl ethyl diethoxy silane, n-hexadecyl ethyl diethoxysilane, n-butyl tripropoxy silane, n-decyl tripropoxy silane andn-hexadecyl tripropoxy silane.

[0214] Desirably, the second photosensitive composition contains theadhesion auxiliary at 0.001 to 10 parts by mass, and preferably 0.001 to5 parts by mass based on 100 parts by mass of the inorganic particles(A).

[0215] (ii) Dispersant:

[0216] The dispersant used for the inorganic particles (A) is preferablya fatty acid; especially it is a fatty acid of 4 to 30 carbon atoms,preferably 4 to 20 carbon atoms. Exemplary preferable fatty acidsinclude saturated fatty acids such as fumaric acid, phthalic acid,malonic acid, itaconic acid, citraconic acid, octanoic acid, undecylicacid, lauric acid, myristic acid, palmitic acid, pentadecanoic acid,stearic acid and arachidic acid; and unsaturated fatty acids such aselaidic acid, oleic acid, linoleic acid, linolenic acid and arachidonicacid. These may be used either singly or in combination of two or morekinds.

[0217] Desirably, the second photosensitive composition contains thedispersant at 0.001 to 10 parts by mass, and preferably 0.01 to 5 partsby mass based on 100 parts by mass of the inorganic particles (A).

[0218] (iii) Filler:

[0219] The filler used herein has a capability of improving thedielectric constant. Examples thereof include conductive fine particlessuch as carbon powders (e.g., acetylene black and Ketjen black),graphite powders and higher order fullerene, and semiconductive fineparticles such as silicone carbide powders.

[0220] Desirably, these fillers for improving the dielectric constantare used at 0 to 10 parts by mass, preferably 0.05 to 3 parts by mass,and particularly preferably 0.1 to 1 part by mass based on 100 parts bymass of the inorganic particles (A).

[0221] <Third Photosensitive Composition For Forming Dielectric>

[0222] The third photosensitive composition for forming a dielectriccomprises:

[0223] (A) inorganic particles which comprise inorganic superfineparticles (A-I) having a mean particle diameter of less than 0.05 μm andinorganic fine particles (A-II) having a mean particle diameter of notless than 0.05 μm;

[0224] (B) an alkali developable resin which is an alkali soluble resin(B2);

[0225] (C) additives which are a compound having an ethylenicallyunsaturated group (C6) and a photopolymerization initiator (C7); andoptionally

[0226] (D) a solvent and

[0227] (E) another additive.

[0228] This third photosensitive composition can be prepared by kneadingthese components with a kneader such as a roll mill, a mixer, ahomomixer, a ball mill or a bead mill.

[0229] The third photosensitive composition thus prepared is in pasteform with a fluidity sufficient for coating applications. Ideally, theviscosity thereof ranges from 10 to 100,000 mPa·s, and preferably from50 to 10,000 mPa·s. Also desirably, this third composition is capable offorming, upon heating at temperatures not higher than 500° C., adielectric that has a dielectric constant of not less than 20 and adielectric loss tangent of not more than 0.1.

[0230] Hereinafter, each component of the third photosensitivecomposition will be descried.

[0231] (A) Inorganic Particles:

[0232] The inorganic particles (A) for the third composition shouldcomprise inorganic superfine particles (A-I) having a mean particlediameter of less than 0.05 μm and inorganic fine particles (A-II) havinga mean particle diameter of not less than 0.05 μm. The inorganicparticles used herein may be those used in the second composition whenthe above conditions are satisfied.

[0233] Desirably, the third photosensitive composition contains theinorganic superfine particles (A-I) at 1 to 30 parts by mass, andpreferably 5 to 20 parts by mass, and the inorganic fine particles(A-II) at 99 to 70 parts by mass, and preferably 95 to 80 parts by masson the basis of 100 parts by mass of the inorganic particles (A). Theuse of the above inorganic particles in the above proportion leads to ahigh packing density of the particles so that the resulting dielectriccan have a high dielectric constant.

[0234] The mean particle diameter of all the inorganic particles, i.e.,that of the whole of the inorganic superfine particles (A-I) and theinorganic fine particles (A-II), is preferably between 0.005 and 2.0 μm,more preferably 0.02 and 1.0 μm, still preferably 0.02 and 0.8 μm andparticularly preferably 0.02 and 0.3 μm. Further, the Dw/Dn ratio (Dw:weight-average particle diameter, Dn: number-average particle diameter)is preferably not less than 1.05, more preferably not less than 1.1,still preferably not less than 1.2, and particularly preferably not lessthan 1.25. With the Dw/Dn ratio being less than 1.05, those dielectricparticles will have a low packing density when a dielectric layer isformed thin so that the leakage current may unfavorably increase.

[0235] In the third composition, the amount of the inorganic particles(A) (total amount of superfine particles (A-I) and fine particles(A-II)) is preferably 20 to 95% by mass, preferably 45 to 90% by mass,and more preferably 55 to 85% by mass based on 100% by mass of the totalamount of the components (A), (B2), (C6) and (C7).

[0236] (B2) Alkali Soluble Resin:

[0237] The alkali soluble resin (B2) used in the third photosensitivecomposition has an “alkali developability”, which is a property of beingdissolved by an alkaline developer. In other words, the alkalidevelopability is understood as an alkali solubility whereby desireddevelopment can be accomplished.

[0238] Various resins can be used as the alkali soluble resin (B2) andexamples thereof include (meth)acrylic resins, hydroxystyrene resins,novolak resins and polyester resins.

[0239] Of these alkali soluble resins (B2), (meth)acrylic resins arepreferable.

[0240] Particularly preferred examples thereof include:

[0241] copolymers comprising a monomer having a carboxyl group (b2)(hereinafter referred to as “monomer (b2)”) and another copolymerizablemonomer (b4) (hereinafter referred to as “monomer (b4)”); and

[0242] copolymers comprising a monomer (b2), a monomer having an OHgroup (b5) (hereinafter referred to as “monomer (b5)”) and a monomer(b4).

[0243] Examples of the monomer (b2) (monomers having a carboxyl group)include those listed with respect to the second photosensitivecomposition.

[0244] Examples of the monomer (b5) (monomers having an OH group)include monomers having a hydroxyl group such as 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl (meth)acrylate and 3-hydroxypropyl(meth)acrylate; and phenolic hydroxyl group-containing monomers such aso-hydroxystyrene, m-hydroxystyrene and p-hydroxystyrene.

[0245] Of these, the monomers having a hydroxyl group such as2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate and3-hydroxypropyl (meth)acrylate are preferred.

[0246] Examples of the monomer (b4) (copolymerizable monomers) includethose listed with respect to the second photosensitive composition.

[0247] Because of the presence of copolymerized components derived froma monomer having a carboxyl group of the monomers (b2) and/or (b5) or aphenolic hydroxyl group, the copolymers comprising the monomers (b2) and(b4) or those comprising the monomers (b2), (b4) and (b5) have thealkali solubility. In particular, the copolymers comprising the monomers(b2), (b4) and (b5) are preferable from the viewpoints of dispersionstability for the inorganic particles (A) and solubility by the alkalinedeveloper after-mentioned. Preferably, the copolymer contains componentunits derived from the monomer (b2) at 1 to 50% by mass, andparticularly preferably 5 to 30% by mass, and those derived from themonomer (b5) at 1 to 50% by mass, and particularly preferably 5 to 30%by mass, and those derived from the monomer (b4) at 1 to 98% by mass,and particularly preferably 40 to 90% by mass.

[0248] The alkali soluble resin (B2) for use in the third compositionpreferably has a mass-average molecular weight in terms of polystyreneas measured by GPC (hereinafter referred to as the “mass-averagemolecular weight (Mw)”) of 5,000 to 5,000,000, and more preferably10,000 to 300,000.

[0249] Desirably, the third photosensitive composition contains thealkali soluble resin (B2) at 1 to 500 parts by mass, preferably 10 to500 parts by mass, and more preferably 10 to 200 parts by mass based on100 parts by weight of the inorganic particles (A).

[0250] Also desirably, the content of the alkali soluble resin (B2) inthe third composition is 1 to 60% by mass, preferably 2 to 30% by mass,and more preferably 5 to 30% by mass based on 100% by mass of the totalamount of the components (A), (B2), (C6) and (C7).

[0251] The third photosensitive composition may contain another resinthan the alkali soluble resin. Examples thereof include polyimideresins, bismaleimide resins and epoxy resins.

[0252] (C6) Ethylenically Unsaturated Group-Containing Compound:

[0253] The ethylenically unsaturated group-containing compound (C6) forthe third composition is not particularly limited as far as it containsan ethylenically unsaturated group and can be induced to undergo radicalpolymerization by the action of a photopolymerization initiator (C7) asdescribed later. However, a (meth)acrylate compound is generally used.

[0254] Examples of the (meth)acrylate compounds include:

[0255] di(meth)acrylates of alkylene glycols, such as of ethylene glycoland propylene glycol;

[0256] di(meth)acrylates of polyalkylene glycols, such as ofpolyethylene glycol and polypropylene glycol;

[0257] di(meth)acrylates of polymers hydroxylated in both terminals,such as of polybutadiene hydroxylated in both terminals, polyisoprenehydroxylated in both terminals and polycaprolactone hydroxylated in bothterminals;

[0258] poly(meth)acrylates of polyvalent alcohols of 3 or more valenciessuch as of glycerol, 1,2,4-butanetriol, trimethylolalkane,tetramethylolalkane, pentaerythritol and dipentaerythritol;

[0259] poly(meth)acrylates of polyalkylene glycol adducts of polyvalentalcohols of 3 or more valencies;

[0260] poly(meth)acrylates of cyclic polyols, such as of1,4-cyclohexanediol and 1,4-benzenediol; and

[0261] oligo-(meth)acrylates, such as polyester (meth)acrylate, epoxy(meth)acrylate, urethane (meth)acrylate, alkyd resin (meth)acrylate,silicone resin (meth)acrylate and spiran resin (meth)acrylate.

[0262] Exemplary (meth)acrylate compounds further include the compoundslisted above as the monomers (b2), (b4) and (b5) for making up thealkali soluble resin (B2).

[0263] The compound having an ethylenically unsaturated group (C6),which includes these (meth)acrylate compounds, may be used either singlyor in combination of two or more kinds. The amount of the compound (C6)is usually 20 to 500 parts by mass, preferably 20 to 480 parts by mass,and more preferably 40 to 250 parts by mass based on 100 parts by massof the alkali soluble resin (B2).

[0264] Also desirably, the content of the compound having anethylenically unsaturated group (C6) in the third composition is 0.1 to30% by mass, preferably 2 to 20% by mass, and more preferably 5 to 15%by mass based on 100% by mass of the total amount of the components (A),(B2), (C6) and (C7).

[0265] (C7) Photopolymerization Initiator:

[0266] The photopolymerization initiator (C7) used in the thirdcomposition generates radicals upon photoexposure as describedhereinbelow to initiate polymerization of the compound having anethylenically unsaturated group (C6). The photopolymerization initiatoris not particularly limited as far as it satisfies the above conditions.

[0267] Examples of the photopolymerization initiator (C7) include:

[0268] carbonyl compounds such as benzyl, benzoin, benzophenone,Michler's ketone, 4,4′-bisdiethylaminobenzophenone, camphorquinone,2-hydroxy-2-methyl-1-phenylpropane-1-one,1-hydroxycyclohexylphenylketone, 2,2-dimethoxy-2-phenylacetophenone,2-methyl-[4′-(methylthio)phenyl]-2-morpholino-1-propane,2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)-butane-1-one,2,4-diethylthioxanthone and isopropylthioxanthone;

[0269] phosphine oxide compounds such asbis(2,6-dimethoxybenzoyl)-2,4,4-trimethylpentylphosphine oxide andbis(2,4,6-trimethylbenzoyl)-phenylphosphine oxide;

[0270] azo or azide compounds such as azoisobutyronitrile and4-azidobenzaldehyde;

[0271] organosulfur compounds such as mercaptan disulfide;

[0272] organic peroxides such as benzoyl peroxide, di-tertbutylperoxide, tert-butyl hydroperoxide, cumene hydroperoxide and paramethanehydroperoxide;

[0273] trihalomethanes such as2,4-bis(trichloromethyl)-6(2′-chlorophenyl)-1,3,5-triadine and2-[2-(2-furanyl)ethylenyl]-4,6-bis(trichloromethyl)-1,3,5-triadine; and

[0274] imidazol dimers such as2,2′-bis(2-chlorophenyl)-4,5,4′,5′-tetraphenyl-1,2′-biimidazol.

[0275] These may be used either singly or in combination of two or morekinds. The photopolymerization initiator (C7) may be used together witha sensitizer, a sensitizing auxiliary, a hydrogen donor or a chaintransfer agent.

[0276] Desirably, the content of the photopolymerization initiator (C7)is 0.1 to 200 parts by mass, and preferably 1 to 50 parts by mass basedon 100 parts by mass of the total amount of the components (B2) and(C6).

[0277] Also desirably, the third photosensitive composition contains thephotopolymerization initiator (C7) at 0.1 to 20% by mass, preferably 0.2to 5% by mass, and more preferably 0.3 to 3% by mass based on 100% bymass of the total amount of the components (A), (B2), (C6) and (C7).

[0278] (D) Solvent:

[0279] The third photosensitive composition may optionally contain asolvent (D).

[0280] The solvent (D) preferably has the following properties:

[0281] it has a good affinity for the inorganic superfine particles(A-I) and the inorganic fine particles (A-II),

[0282] it has a good solubility for the alkali soluble resin (B2), thecompound having an ethylenically unsaturated group (C6), thephotopolymerization initiator (C7) and a later-mentioned optionaladditive (E),

[0283] it can impart an appropriate viscosity to the thirdphotosensitive composition, and

[0284] it can be readily evaporated by drying.

[0285] Examples of the solvent (D) include those listed with respect tothe second composition. Those solvents may be used either singly or incombination of two or more kinds.

[0286] The content of the solvent (D) in the third composition can beappropriately determined to obtain an good flowability. Desirably, it isin the range of 1 to 10,000 parts by mass, and preferably 10 to 1,000parts by mass based on 100 parts by mass of the inorganic particles (A).

[0287] (E) Another Additive:

[0288] In addition to the above components (A), (B2), (C6) and (C7), thethird photosensitive composition may optionally contain another additive(E). Examples thereof include a plasticizer, an adhesion auxiliary, adispersant, a filler, a storage stabilizer, an anti-foaming agent, anantioxidant, an ultraviolet light absorber, a leveling agent and adeveloping accelerator.

[0289] (i) Adhesion Auxiliary:

[0290] The adhesion auxiliary used in the third composition can beexemplified with the same compounds listed with respect to the secondcomposition. Desirably, the third composition contains the adhesionauxiliary at 0.001 to 10 parts by mass, and preferably 0.001 to 5 partsby mass based on 100 parts by mass of the inorganic particles (A).

[0291] (ii) Dispersant:

[0292] The dispersant used for the inorganic particles (A) in the thirdcomposition can be exemplified with the same compounds listed withrespect to the second composition. Desirably, the third compositioncontains the dispersant at 0.001 to 10 parts by mass, and preferably0.01 to 5 parts by mass based on 100 parts by mass of the inorganicparticles (A).

[0293] (iii) Filler:

[0294] The filler used in the third composition can be exemplified withthe same compounds listed with respect to the second composition.Desirably, the third composition contains the filler at 0 to 10 parts bymass, preferably 0.05 to 3 parts by mass, and particularly preferably0.1 to 1 part by mass based on 100 parts by mass of the inorganicparticles (A).

[0295] <Photosensitive Transfer Film>

[0296] The photosensitive transfer film according to the invention canbe obtained by applying the aforesaid second photosensitive compositiononto a substrate film to form a photosensitive transfer layer on thesubstrate film. The photosensitive transfer layer may be overlaid with aprotective film.

[0297] (Substrate Film and Protective Film)

[0298] The substrate film of the photosensitive transfer film ispreferably a resin film with heat and solvent resistances and alsoflexibility. A conductive foil is also preferable. The flexibility ofthe substrate film allows for application of the pasty composition withuse of a roll coater to form a photosensitive transfer layer. Further,it enables storage and supply of the rolled photosensitive transferlayer.

[0299] The substrate film consisting of a conductive foil is employableas follows:

[0300] a dielectric layer which have been applied on the conductive foilis adhered to another substrate, and then the conductive foil ispatterned with use of another dry film photoresist (DFR). The patternedconductive foil is used as a photomask in exposing the dielectric layer.Further, the patterned conductive foil can be used as a upper electrodefor the dielectric layer.

[0301] Exemplary resins for making the substrate film includepolyethylene terephthalates, polyesters, polyethylenes, polypropylenes,polystyrenes, polyimides, polyvinyl alcohols, fluorine-containing resins(such as polyfluoroethylene), nylons and celluloses. The substrate filmdesirably ranges in thickness from 20 to 100 μm, and preferably from 25to 50 μm from the viewpoint of strength and the like. It is preferablethat a surface of the substrate resin film has been release-treated. Therelease treatment enables easy release of the substrate film whenforming a pattern according to the method described hereinbelow. Forexample, the release treatment can be suitably accomplished byapplication of a release agent such as a silicon release agent, afluorine release agent or a silicon-fluorine release agent.

[0302] Exemplary conductive foils employable as the substrate filminclude those comprising copper, gold, silver, platinum, nickel,stainless steel, aluminum, iron or various alloys. From the viewpoint ofoxidation resistance, conductivity and flexibility, the foil comprisingcopper, gold, silver, platinum, nickel or aluminum are particularlypreferable. The conductive substrate foil may be a laminate of pluralconductive foils or a laminate of the conductive foil and either a resinsubstrate or a substrate given by impregnating a nonwoven with a resin.Desirably, the conductive foil has a thickness of, but not particularlylimited thereto, 5 to 75 μm, preferably 8 to 50 μm, and particularlypreferably 10 to 25 μm.

[0303] The protective film may comprise the same material as that of thesubstrate film. A surface of the protective film also isrelease-treated. The peeling strength with respect to the protectivefilm and the photosensitive transfer layer should be lower than thatwith respect to the substrate film and the photosensitive transferlayer.

[0304] (Photosensitive Transfer Layer)

[0305] The photosensitive transfer layer of the photosensitive transferfilm can be prepared by applying the above photosensitive composition onthe substrate film and drying the applied composition to partially orcompletely remove the solvent.

[0306] To obtain the photosensitive transfer layer as described above,the aforesaid composition is preferably applied on the substrate film bya method capable of effectively forming a uniform and thick layer (forexample not less than 1 μm). Exemplary preferred coating methods includethe use of a roll coater, a blade coater, a slit coater, a curtaincoater and a wire coater.

[0307] In respect to the drying conditions, the drying temperature andtime may range from 50 to 150° C. and from about 0.5 to 30 minutes,respectively. Desirably, the amount of residual solvent (with respect tothe dried photosensitive transfer layer) will be not more than 2% bymass, and preferably not more than 1% by mass.

[0308] The photosensitive transfer layer is thus formed on at least onesurface of the substrate film. Desirably, the transfer layer has athickness of 1 to 100 μm, preferably 3 to 70 μm, and more preferably 5to 50 μm.

[0309] Also desirably, the photosensitive transfer layer contains theinorganic particles (A) at 30 to 90% by mass, and preferably 40 to 80%by mass based on the amount of the transfer layer. The photosensitivefilm has the photosensitive transfer layer described above and hasexcellent adhesion to an objective substrate and can be formed into apattern with high dimensional precision.

[0310] <Dielectric>

[0311] The aforesaid photosensitive compositions can form a dielectricby heating at 500° C. or below. This dielectric has a dielectricconstant of not less than 5 and a dielectric loss tangent of not morethan 0.1. In particular, the first photosensitive composition can beheated at 500° C. or below to form a dielectric that has a dielectricconstant of not less than 5, preferably not less than 10, a dielectricloss tangent of not more than 0.1, and an electrostatic capacity of notless than 5 nF/cm². The second or third photosensitive composition orthe photosensitive transfer film, when heated at 500° C. or below,provides a dielectric that has a dielectric constant of not less than 20and a dielectric loss tangent of not more than 0.1.

[0312] Preparation methods and properties of these dielectrics will bedescribed hereinbelow.

[0313] <Dielectric Prepared From First Photosensitive Composition>

[0314] (Method of Forming a Dielectric Pattern)

[0315] The method for forming a dielectric pattern from the firstphotosensitive composition comprises the steps of (1) applying thecomposition, (2) photoexposing the resultant dielectric layer, (3)developing the dielectric layer, and (4) curing the dielectric pattern.

[0316] (1) Step of Applying the Photosensitive Composition:

[0317] In this step, the first composition is applied onto a substratesuch as a silicon wafer on which wiring patterns have been provided.Then the applied composition is dried to evaporate the solvent, etc toform a coating layer. This application may be accomplished by, forexample, dip coating, spray coating, bar coating, roll coating, spincoating, curtain coating or screen printing. The thickness of thecoating layer can be controlled appropriately by selecting theapplication method and adjusting the solid concentration or viscosity ofthe composition.

[0318] The above substrate is not particularly limited. For example, itmay be a plate such as a printed-wiring board, a copper-clad laminate(CCL), an SUS substrate, a copper-foiled polyimide substrate, a ceramicsubstrate, a silicon wafer (e.g., W-CSP) or an alumina substrate.

[0319] (2) Step of Photoexposing the Dielectric Layer:

[0320] The dielectric layer obtained by the above application step isselectively irradiated with (exposed to) radiation through a desiredpattern mask. Thus, a latent pattern image can be formed on thedielectric layer.

[0321] Exemplary radiations employable for the above exposure include anultraviolet ray, an electron beam and a laser beam emitted from alow-pressure mercury lamp, a high-pressure mercury lamp, a metal halidelamp, a g-line stepper and an i-line stepper. The dose can beappropriately determined in accordance with the radiation source used orthe thickness of the dielectric layer. In the case of ultraviolet raysradiated from high-pressure mercury lamps, the dose is about 1,000 to20,000 J/m² for the dielectric layer thickness of 0.5 to 50 μm.

[0322] (3) Step of Developing the Dielectric Layer:

[0323] The photoexposed dielectric layer is subjected to development inwhich a photoexposed area is dissolved with an alkaline developer andwashed away. Thus, a coating layer in desired pattern can be obtained.

[0324] Since the inorganic particles (A) have been uniformly dispersedin the phenolic resin (B1), it is naturally understood that when thedielectric layer is developed by dissolving and washing away the binderphenolic resin (B1), the inorganic particles (A) present in thedissolved area will also be removed at the same time. Exemplarydeveloping methods include shower development, spray development,immersion development and puddle development. The development is usuallycarried out at 20 to 40° C. for about 1 to 10 minutes.

[0325] Examples of the alkaline developer include alkaline aqueoussolutions of about 0.1 to 10% by mass of an alkaline compound, such asof sodium hydroxide, potassium hydroxide, ammonia water,tetramethylammonium hydroxide or choline. The alkaline aqueous solutionmay be mixed with an appropriate amount of water-soluble organicsolvent, such as methanol or ethanol, or a surfactant. The abovedevelopment with the alkaline developer is followed by water washing anddrying.

[0326] (4) Step of Curing the Dielectric Pattern:

[0327] In order to impart a function as an electrical condenser, thedeveloped pattern is then cured by heat treatment to give a cured layer.On heating, the acid generator (C3) is decomposed to generate an acid.The catalysis of this acid accelerates a curing reaction between thecuring agent (C2) and the phenolic resin (B1). The curing conditions arenot particularly limited and depend on the objective use of curedproduct; for example the coating layer may be cured by heating at 100 to250° C. for 30 minutes to 10 hours. It is also possible to carry out theheat treatment in two stages in order to effect the curing sufficientlyor to avoid deformation of the resulting pattern. For example, thecuring can be carried out in a manner such that the dielectric patternis heated at 50 to 100° C. for 10 minutes to 2 hours in the first stageand further at 100 to 250° C. for 20 minutes to 8 hours in the secondstage. With the above curing conditions, the heating can be conducted bya conventional oven, an infrared oven or the like.

[0328] (Properties of the Dielectric)

[0329] The dielectric prepared from the first composition desirably hasa dielectric constant of not less than 5, preferably not less than 10,and more preferably not less than 15. The upper limit of the dielectricconstant is not particularly limited. That is, there is no problem forthe dielectric constant to be about 200.

[0330] Also, the dielectric obtained from the first compositiondesirably has a dielectric loss tangent of not more than 0.1, preferablynot more than 0.08, and still preferably not more than 0.06. The lowerlimit of the dielectric loss tangent is not particularly limited. Thatis, there is no problem for the dielectric loss tangent to be about0.001.

[0331] Further, the dielectric produced from the first compositiondesirably has an electrostatic capacity of not less than 5 nF/cm²,preferably not less than 10 nF/cm², and more preferably not less than 15nF/cm². The upper limit of the electrostatic capacity is notparticularly limited. That is, there is no problem for the electrostaticcapacity to be about 50 nF/cm² or more.

[0332] The dielectric constant, dielectric loss tangent andelectrostatic capacity as used in the present specification are measuredby the methods described in JIS K6481 (at 1 MHz frequency).

[0333] To be used as an electrical condenser, the above dielectricpreferably has a leakage current of not more than 10⁻⁸ A/cm², stillpreferably not more than 10⁻⁹ A/cm², and even preferably not more than10⁻¹⁰ A/cm².

[0334] Preferably, the dielectric has a thickness of not more than 50μm, still preferably not more than 20 μm, and even preferably not morethan 5 μm. The lower limit of the thickness is not particularly limited,but the thickness is usually not less than 0.5 μm.

<Dielectric Prepared From Second Or Third Photosensitive Composition>

[0335] (Method of Forming a Dielectric Pattern)

[0336] The method for forming a dielectric pattern from the second orthird photosensitive composition comprises the steps of either (1-1)applying the composition or (1-2) transferring the photosensitivetransfer layer, and (2) photoexposing the resultant dielectric layer,(3) developing the dielectric layer, and (4) curing the dielectricpattern.

[0337] (1-1) Step of Applying the Photosensitive Composition:

[0338] In this step, the second or third composition is applied by acoater onto a substrate to form a dielectric layer. Exemplary preferredcoaters include a spinner, a screen printer, a gravure coater, a rollcoater, a bar coater and a die coater.

[0339] The substrate to be coated with the second composition is notparticularly limited. For example, it may be a plate such as aprinted-wiring board, a copper-clad laminate (CCL), an SUS substrate, acopper-foiled polyimide substrate, a ceramic substrate, a silicon wafer(e.g., W-CSP) or an alumina substrate. The substrate used in the case ofthe third composition may be a plate substrate comprising, but notparticularly limited thereto, a printed-wiring board, a silicon wafer(e.g., W-CSP), a glass substrate or an alumina substrate.

[0340] Specifically, the second or third photosensitive composition isprinted on the substrate, e.g., printed-wiring board, with a screenprinter etc. and thereafter dried in an oven or the like to form adielectric layer.

[0341] (1-2) Step of Transferring the Photosensitive Transfer Layer:

[0342] In this step, the photosensitive transfer layer of thephotosensitive transfer film is transferred on a substrate.

[0343] The substrate used herein may be a plate substrate of the samekind as the one coated with the second composition. It is permissiblethat a desired pattern has been formed on the surface of the platesubstrate. When required, the surface of the substrate may be pretreatedby chemical treatment with a silane coupling agent or the like, plasmatreatment, or thin-film forming treatment by ion plating, sputtering,vapor phase reaction or vacuum deposition.

[0344] An exemplary transfer process is given below:

[0345] when the protective film has been provided due to need, the filmis peeled from the photosensitive transfer film;

[0346] the photosensitive transfer film is superposed on the substrateso that the transfer layer will be in contact with the substrate; and

[0347] the photosensitive transfer film is thermocompression bonded withthe substrate by means of a heating roller or the like.

[0348] By this process, the photosensitive transfer layer is transferredon the substrate and adheres thereto.

[0349] The transferring conditions are such that the heating roller hasa surface temperature of 20 to 140° C., a rolling pressure of 1 to 5kg/cm², and a traveling speed of 0.1 to 10.0 m/min. It is possible thatthe substrate has been preheated, for example at 40 to 100° C.

[0350] (2) Step of Photoexposing the Dielectric Layer:

[0351] The dielectric layer obtained as above is irradiated with(exposed to) radiation through a photomask in a selected area. Thus, alatent pattern image can be formed on the dielectric layer.

[0352] When the dielectric layer is produced from the secondphotosensitive composition, a conductive foil may be provided on thedielectric layer during the production. This dielectric layer withconductive foil may be prepared by either laminating a conductive foilwith a DFR on the dielectric layer obtained in the aforesaid step (1-1)or by using a conductive foil as the substrate film in the aforesaidstep (1-2). This laminate is then subjected to chemical etching of theconductive foil along a previously made pattern. The resultantconductive foil pattern may be used as the above photomask.

[0353] Exemplary radiations employable for the above selectiveirradiation (exposure) include a visible ray, an ultraviolet ray, a farinfrared ray, an electron beam and a X-ray. Of these, a visible ray, anultraviolet ray and a far infrared ray are preferable; an ultravioletray is more preferably used.

[0354] The photomask has open square dots ranging from 10 to 1000 μm,but the exposure pattern may differ depending on the object.

[0355] The irradiation equipment may be, but not particularly limitedto, an ultraviolet irradiation equipment used in the photolithographyprocess or an aligner used in the production of semiconductors andliquid crystal displays.

[0356] (3) Step of Developing the Dielectric Layer:

[0357] The photoexposed dielectric layer is then developed to elicit thepattern (latent image) in the dielectric layer.

[0358] The developer used in this development can be an alkalinedeveloper. By the use thereof, the alkali-developable resin (B)contained in the dielectric layer can be readily dissolved and washedaway.

[0359] Since the inorganic superfine particles (A-I) and the inorganicfine particles (A-II) have been uniformly dispersed in the alkalidevelopable resin (B), it is naturally understood that when thedielectric layer is developed by dissolving and washing away thealkali-developable binder resin (B), the particles (A-I) and (A-II)present in the dissolved area will also be removed at the same time.

[0360] Exemplary active ingredients of the alkaline developer include:

[0361] inorganic alkaline compounds such as lithium hydroxide, sodiumhydroxide, potassium hydroxide, sodium hydrogen phosphate, diammoniumhydrogen phosphate, dipotassium hydrogen phosphate, disodium hydrogenphosphate, ammonium dihydrogen phosphate, potassium dihydrogenphosphate, sodium dihydrogen phosphate, lithium silicate, sodiumsilicate, potassium silicate, lithium carbonate, sodium carbonate,potassium carbonate, lithium borate, sodium borate, potassium borate andammonia; and

[0362] organic alkaline compounds such as tetramethylammonium hydroxide,trimethylhydroxyethylammonium hydroxide, monomethylamine, dimethylamine,trimethylamine, monoethylamine, diethylamine, triethylamine,monoisopropylamine, diisopropylamine and ethanolamine.

[0363] The alkaline developer for use in the above development can beprepared by dissolving at least one of these alkaline compounds in asolvent such as water. The concentration of the alkaline compound(s) inthe alkaline developer is usually 0.001 to 10% by mass, and preferably0.01 to 5% by mass. The alkaline developer may contain an additive suchas a nonionic surfactant or an organic solvent.

[0364] The above development with the alkaline developer will be usuallyfollowed by water washing. According to necessity, undesired residuesleft on the sidewalls of the patterned dielectric layer or on theuncoated area of substrate may be rubbed off by a separate step.

[0365] With respect to the development conditions, the kind, compositionand concentration of the developer; the development time, temperatureand method (such as immersion development, rocking development, showerdevelopment, spray development or puddle development); and thedevelopment apparatus may be selected appropriately depending onpurpose.

[0366] By the above development, a dielectric pattern consisting ofremoved and remaining portions of the dielectric layer can be formed asdesigned by the photomask.

[0367] (4) Step of Curing the Dielectric Pattern:

[0368] The dielectric pattern is subjected to a heat treatment and thepattern is cured. This thermal curing can be accomplished by heating attemperatures not higher than 500° C., preferably from 100 to 500° C.,and more preferably from 150 to 300° C. The heating time is preferably 1minute to 24 hours, and more preferably 10 minutes to 12 hours.

[0369] Exemplary heating means for thermally curing the second or thirdcomposition include an oven, an infrared oven and a hot plate.

[0370] (Properties of the Dielectric)

[0371] The dielectric prepared from the second or third composition orfrom the photosensitive transfer film desirably has a dielectricconstant of not less than 20, preferably not less than 23, morepreferably not less than 25, and particularly preferably not less than30. The upper limit of the dielectric constant is not particularlylimited. That is, there is no problem for the dielectric constant to beabout 200.

[0372] The dielectric obtained from the second or third composition orfrom the photosensitive transfer film desirably has a dielectric losstangent of not more than 0.1, preferably not more than 0.08, and stillpreferably not more than 0.06. The lower limit of the dielectric losstangent is not particularly limited. That is, there is no problem forthe dielectric loss tangent to be about 0.001.

[0373] The dielectric constant and dielectric loss tangent as used inthe present specification are measured by the methods described in JISK6481 (at 1 MHz frequency).

[0374] To be used as an electrical condenser, the above dielectricpreferably has a leakage current of not more than 10⁻⁹ A/cm², stillpreferably not more than 10⁻¹⁰ A/cm², and even preferably not more than10⁻¹¹ A/cm².

[0375] Preferably, the dielectric has a thickness of not more than 20μm, and still preferably not more than 10 μm. The lower limit of thethickness is not particularly limited, but the thickness is usually notless than lam.

<Electronic Parts>

[0376] The first photosensitive composition can be calcined at lowtemperatures not higher than 500° C. to form the dielectric, and theresultant dielectric has a dielectric constant of not less than 5, adielectric loss tangent of not more than 0.1 and an electrostaticcapacity of not less than 4 nF/cm². Further, the second or thirdphotosensitive composition or the photosensitive transfer film can becalcined at low temperatures not higher than 500° C. to form thedielectric, and the resultant dielectric has a dielectric constant ofnot less than 20 and a dielectric loss tangent of not more than 0.1.Therefore, electronic parts, such as an electrical condenser that isthin and has a large electrostatic capacity, are produced from the abovedielectric. Moreover, the dielectric according to the invention allowsfor miniaturization and high-densification of electronic parts such as aprinted circuit board, a semiconductor package, an electrical condenserand a high-frequency antenna.

INDUSTRIAL APPLICABILITY

[0377] The photosensitive compositions of the invention can form, uponheating at low temperatures of 500° C. or below, a dielectric that has adielectric constant of not less than 5 and a dielectric loss tangent ofnot more than 0.1. The first photosensitive composition can be heated atlow temperatures not higher than 500° C. to produce a dielectric thathas a dielectric loss tangent of not more than 0.1 and a highelectrostatic capacity of not less than 5 nF/cm². The second or thirdphotosensitive composition or the photosensitive transfer film can form,upon heating at low temperatures of 500° C. or below, a dielectric thathas a low dielectric loss tangent of not more than 0.1 and a highdielectric constant of not less than 20.

[0378] The dielectric of the invention is thin and has a high dielectricconstant, so that it can be suitably used in electronic parts such as aprinted wiring board, a semiconductor package, an electrical condenserand a high-frequency antenna.

[0379] The electronic parts of the invention can be fabricated small andthinly by the use of the above dielectric.

EXAMPLES

[0380] The present invention will be hereinafter described in detail bythe following Examples, but it should be construed that the invention isin no way limited to those Examples. Hereinafter, “parts” and “%” are bymass unless otherwise mentioned.

[0381] The mass-average molecular weight (Mw) is in terms of polystyrenemeasured by a gel permeation chromatography (GPC) using a chromatographHLC-802A (available from TOSOH CORPORATION).

[0382] Patterning properties and dielectric properties of the dielectricpatterns were evaluated as follows.

[0383] (Patterning Properties)

[0384] In each Example and Comparative Example, measurements werecarried out for the width and height of the obtained dielectric patternwith a scanning electron microscope (SEM) to evaluate the accuracy ofpattern width as “AA” for the width of 500±10 μm and “BB” for others.Also, deletion of pattern was visually evaluated as “AA” fornon-deletion and “BB” for deletion.

[0385] (Dielectric Constant, Dielectric Loss Tangent and LeakageCurrent)

[0386] Preparation of Electrode:

[0387] In Examples 1-10 and Comparative Examples 1-6, the dielectricpattern obtained was aluminized to form an upper electrode (thickness:0.5 μm) on the dielectric pattern. In Examples 11-13 and ComparativeExample 7, copper-foiled dielectric patterns were afforded to use thecopper foil on the pattern as an upper electrode. In Examples 14-17 andReference Examples 1-2, the dielectric pattern obtained was aluminizedto form an electrode having a guide ring (area: 1 cm², thickness: 0.1μm).

[0388] Measurements of Dielectric Constant and Dielectric Loss Tangent:

[0389] The dielectric constant and the dielectric loss tangent weremeasured at 1 MHz by an LCR meter (HP4284A available fromHewlett-Packard Company). The above measurements were carried out withrespect to 10 measurement points between the copper foiled side and theupper electrode of the printed wiring board or silicon wafer substrate.The obtained values were averaged to determine the dielectric constantand the dielectric loss tangent.

[0390] Measurement of Leakage Current:

[0391] The leakage current was measured with respect to 10 measurementpoints between the copper foiled side and the electrode with the use ofan insulation resistance tester (a product of Advantest Corporation).The obtained values were averaged to determine the leakage current.

[0392] (Moist Heat Resistance (HAST test))

[0393] The cured films were subjected to a 72-hour moist heat resistancetest at 121° C. and 100% humidity under 2 atm. The films given beforeand after the test were individually analyzed by an infraredspectrophotometry. The results were compared with each other to evaluatethe moist heat resistance according to the following criteria.

[0394] AA: no difference observed, showing good moist heat resistance

[0395] BB: drastic difference observed, showing poor moist heatresistance

[0396] <First Photosensitive Composition For Forming Dielectric>

[0397] The following is a list of the components used in Examples 1-5and Comparative Examples 1-5.

[0398] Inorganic Particles (A):

[0399] A-1: barium titanate particles (trade name: BT-01 available fromSakai Chemicals Co., Ltd., mean particle diameter: 0.1 μm)

[0400] A-2: barium titanate particles (trade name: BT-02 available fromSakai Chemicals Co., Ltd., mean particle diameter: 0.2 μm)

[0401] Phenolic Resin (B1):

[0402] B1-1: cresol novolak resin prepared from m-cresol and p-cresol in60/40 molar ratio (mass-average molecular weight in terms ofpolystyrene: 8,700)

[0403] B1-2: cresol novolak resin prepared from m-cresol and p-cresol in50/50 molar ratio (mass-average molecular weight in terms ofpolystyrene: 7,500)

[0404] B1-3: polyhydroxystyrene (trade name: MARUKA LYNCUR S-2Pavailable from Maruzen Petrochemical Co., Ltd.)

[0405] Phenolic Compound (b1):

[0406] b1-1:1,1-bis(4-hydroxyphenyl)-1-[4-{1-(4-hydroxyphenyl)-1-methylethyl}phenyl]ethane

[0407] Quinonediazide Compound (C1):

[0408] C1-1: condensate formed between1,1-bis(4-hydroxyphenyl)-1-[4-[1-(4-hydroxyphenyl)-1-methylethyl]phenyl]ethaneand 1,2-naphthoquinonediazido-5-sulfonic acid in an average molar ratioof 1/2.0

[0409] C1-2: condensate formed between1,1-bis(4-hydroxyphenyl)-1-phenylethane and1,2-naphthoquinonediazido-5-sulfonic acid in an average molar ratio of1/1.5

[0410] Curing Agent (C2):

[0411] C2-1: hexamethoxymethylated melamine (trade name: CYMEL 300available from Mitsui Cytec, Ltd.)

[0412] C2-2: tetramethoxymethyl glycoluril (trade name: CYMEL 1174available from Mitsui Cytec, Ltd.)

[0413] Acid Generator (C3):

[0414] C3-1: benzyl(4-hydroxyphenyl)methylsulfonium hexafluoroantimonate

[0415] C3-2: benzyl(4-hydroxyphenyl)methylsulfonium hexafluorophosphate

[0416] Crosslinked Fine Particles (C4):

[0417] C4-1: butadiene/hydroxybutyl methacrylate/methacrylicacid/divinylbenzene=60/32/6/2 (wt %), mean particle diameter=65 nm

[0418] Solvent (D):

[0419] D-1: ethyl lactate

[0420] D-2:2-heptanone

Examples 1-5

[0421] (1) Preparation of Photosensitive Composition for FormingDielectric

[0422] The inorganic particles (A), phenolic resin (B1), phenoliccompound (b1), quinonediazide compound (C1), curing agent (C2), acidgenerator (C3) and crosslinked fine particles (C4) were dissolved in thesolvent (D) in the mixing ratio listed in Table 1. The solution waskneaded in a bead mill and thereafter filtered through a stainless steelmesh (500 mesh) and a filter having a pore size of 1 μm to prepare aphotosensitive composition for forming a dielectric.

[0423] (2) Application of Photosensitive Composition for FormingDielectric

[0424] The above photosensitive composition was applied by a spinneronto a Cu-sputtered silicon water. The applied composition was dried at100° C. for 5 minutes to remove the solvent. As a result, aphotosensitive dielectric layer was formed in a thickness of 1 μm.

[0425] (3) Photoexposure and Development of Dielectric Layer

[0426] The photosensitive dielectric layer was irradiated with i-lineradiation (ultraviolet ray of 365 nm wavelength) through a photomask(having a pattern with 500 μm squares dots) by use of an ultrahighpressure mercury lamp. The dose was 500 mJ/cm².

[0427] After the completion of the photoexposure, the photoexposeddielectric layer was treated by a shower development for 2 minutes withan aqueous solution of 2.38% by mass of tetramethylammonium hydroxide(25° C.) as the developer. Thereafter the dielectric layer was washedwith ultrapure water to remove the area that had been solubilized byultraviolet irradiation. Thus, a pattern was formed.

[0428] (4) Curing of Dielectric Pattern

[0429] The patterned dielectric layer on the silicon wafer was cured inan oven at 200° C. for 60 minutes to form a dielectric pattern on thesubstrate.

[0430] The patterning properties and dielectric properties of theobtained dielectric pattern were measured by the above methods. Theresults are shown in Table 1.

Comparative Examples 1-5

[0431] In the same manner as in the above Examples, a composition wasprepared in the mixing ratio listed in Table 2. The properties weremeasured in the same manner. The results are shown in Table 2. TABLE 1Ex. 1 Ex. 2 Ex. 3 Ex. 4 Ex. 5 Photosensitive composition for formingdielectric Component Type PBW* Type PBW* Type PBW* Type PBW* Type PBW*(A) Inorganic particles A-1 150 A-1 350 A-2 150 A-1 150 A-1 150 (B1)Phenolic resin B1-1 100 B1-1 100 B1-1  90 B1-2 100 B1-1/B1-2 90/10 (b1)Phenolic compound — — — — b1-1  10 — — — — (C1) Quinonediazido compoundC1-1  15 C1-1  15 C1-1  15 C1-2  15 C1-1  15 (C2) Curing agent C2-1  23C2-1  23 C2-2  23 C2-1  23 C2-1  23 (C3) Acid generator C3-1  2 C3-1  2C3-1  2 C3-2  2 C3-2  2 (C4) Crosslinked fine C4-1  10 C4-1  10 C4-1  10— — C4-1  10 particles (D) Solvent D-1 900 D-1 900 D-2 900 D-2 900 D-2900 Patterning properties Patterning accuracy AA AA AA AA AA Patterndeletion AA AA AA AA AA Characteristics of dielectric Thickness (μm) 1 11 0.7 2 Dielectric constant 10 20 13 10 10 Dielectric loss tangent 0.050.07 0.05 0.04 0.04 Electrostatic capacity (nF/cm²) 10 20 13 14 5 Moistheat resistance AA AA AA AA AA Leakage current (A/cm²) 10⁻¹⁰ 10⁻¹⁰ 10⁻¹⁰10⁻¹⁰ 10⁻¹⁰

[0432] TABLE 2 Comp. Ex. 1 Comp. Ex. 2 Comp. Ex. 3 Comp. Ex. 4 Comp. Ex.5 Photosensitive composition for forming dielectric Component Type PBW*Type PBW* Type PBW* Type PBW* Type PBW* (A) Inorganic particles A-1 150A-1 150 A-2 150 A-1 150 A-1 150 (B1) Phenolic resin — — B1-1 100 B1-1 90 B1-1 100 B1-1/B1-2 90/10 (b1) Phenolic compound — — — — b1-1  10 — —— — (C1) Quinonediazido compound C1-1  15 C1-1  15 C1-1  15 — — C1-1  15(C2) Curing agent C2-1  23 — — C2-2  23 C2-1  23 — — (C3) Acid generatorC3-2  2 — — — — C3-2  2 C3-2  2 (C4) Crosslinked fine C4-1  10 C4-1  10C4-1  10 C4-1  5 C4-1  10 particles (D) Solvent D-1 900 D-1 900 D-2 900D-2 900 D-2 900 Patterning properties Patterning accuracy BB BB BB BB AAPattern deletion — BB BB — AA Characteristics of dielectric Thickness(μm) 1 1 1 1 1 Dielectric constant 4 8 13 12 6 Dielectric loss tangent0.15 0.07 0.05 0.04 0.04 Electrostatic capacity (nF/cm²) 4 8 13 12 6Moist heat resistance BB BB AA AA BB Leakage current (A/cm²) 10⁻⁷ 10⁻⁸10⁻¹⁰ 10⁻⁸ 10⁻⁸

[0433] <Second Photosensitive Composition For Forming Dielectric>

[0434] The following are a list of the components used in Examples 6-13and Comparative Examples 6-7 and descriptions of the synthesis of thealkali developable resins (B) used in those embodiments.

[0435] Inorganic Particles (A):

[0436] A-1: barium titanate particles (trade name: BT-01 available fromSakai Chemicals Co., Ltd., mean particle diameter: 0.1 μm, dielectricconstant: 500)

[0437] A-2: barium titanate particles (trade name: BT-02 available fromSakai Chemicals Co., Ltd., mean particle diameter: 0.2 μm, dielectricconstant: 500)

[0438] A-3: barium titanate nanoparticles (Nisshin Engineering Inc.,mean particle diameter: 0.03 μm, dielectric constant: 400)

[0439] A-4: barium titanate particles (TOHO TITANIUM CO., LTD., meanparticle diameter: 0.1 μm, dielectric constant: 400)

[0440] A-5: titania nanoparticles (trade name: RTIPBC available fromC.I. KASEI CO., LTD., mean particle diameter: 0.02 μm, dielectricconstant: 100)

[0441] Photoacid Generator (C5):

[0442] C5-1: ester of4,4′-[1-[4-(1-(4-hydroxyphenyl)-1-methylethyl)phenyl]ethylidene]diphenolwith 1,2-naphthoquinonediazido-5-sulfonic acid (average esterificationratio: 66.7 mol %)

[0443] Solvent (D):

[0444] D-1: ethyl lactate

[0445] D-3: propylene glycol monomethyl ether

[0446] Alkali Developable Resin (B):

Synthesis Example 1

[0447] A flask purged with nitrogen was charged with 459.0 g of adiethylene glycol dimethyl ether solution in which 9.0 g of2,2′-azobisisobutyronitrile had been dissolved. Further, 22.5 g ofstyrene, 45.0 g of methacrylic acid, 67.5 g of dicyclopentanylmethacrylate and 90.0 g of glycidyl methacrylate were added thereto.Then the mixture solution was stirred slowly, and the solution washeated to 80° C., maintained at this temperature for 5 hours and heatedat 90° C. for 1 hour to complete the polymerization.

[0448] The solution obtained by the above reaction was added dropwise toa large quantity of water to solidify the reaction product. The reactionproduct was washed with water, redissolved in 200 g of tetrahydrofuran,and resolidified in a large amount of water. This operation throughredissolution to resolidification was repeated three times. Thereafter,the resultant solidified product was vacuum dried at 60° C. for 48 hoursto yield a copolymer (I).

Synthesis Example 2

[0449] A flask purged with nitrogen was charged with 459.0 g of a methyl3-methoxypropionate solution in which 9.0 g of2,2′-azobisisobutyronitrile had been dissolved. Further, 56.25 g ofmethacrylic acid, 90.0 g of methyl methacrylate and 78.75 g of3,4-epoxybutyl methacrylate were added thereto. Then the mixturesolution was stirred slowly, and the polymerization was initiated byheating the solution to 80° C. The solution was maintained at thistemperature for 5 hours and heated at 90° C. for 1 hour to complete thepolymerization. The resultant solution was treated in the same manner asin Synthesis Example 1 to yield a copolymer (II).

Synthesis Example 3

[0450] 32.29 g (90 mmol) of 3,3′,4,4′-diphenylsulfonetetracarboxylicdianhydride and 3.00 g (10 mmol) of1,3,3a,4,5,9A-hexahydro-5(tetrahydro-2,5-dioxo-3-furanyl)-naphtho[1,2-c]-furan-1,3-dioneas tetracarboxylic dianhydrides; 28.74 g (70 mmol) of2,2-bis[4-(4-aminophenoxy)phenyl]propane as a diamine compound, 2.49 g(10 mmol) of organosiloxane LP7100 (available from Shin-Etsu Chemical,Co., Ltd.); and 3.04 g (20 mmol) of 3,5-diaminobenzoic acid weredissolved in 450 g of N-methyl-2-pyrrolidone (NMP) and reacted with eachother for 12 hours at room temperature. Thereafter, 32 g of pyridine and71 g of acetic anhydride were added to the reaction solution, andcyclodehydration was carried out at 100° C. for 3 hours. The resultantreaction solution was purified by vacuum distillation to obtain an NMPsolution of polyimide with 20% solid concentration.

Example 6

[0451] (1) Preparation of Photosensitive Composition for Forming aDielectric

[0452] The inorganic superfine particles (A-I), inorganic fine particles(A-II), alkali developable resin (B), photoacid generator (C5) andsolvent (D) in the mixing ratio listed in Table 3 were kneaded in a beadmill. The mixture was thereafter filtered through a stainless steel mesh(500 mesh) and a filter having a pore size of 1 μm to prepare aphotosensitive composition for forming a dielectric.

[0453] (2) Application of Photosensitive Composition for Forming aDielectric

[0454] The above photosensitive composition was applied by a spinneronto a printed wiring board. The applied composition was dried at 100°C. for 5 minutes to remove the solvent. As a result, a photosensitivedielectric layer was formed in a thickness of 7 μm.

[0455] (3) Photoexposure and Development of Dielectric Layer

[0456] The photosensitive dielectric layer was irradiated with i-lineradiation (ultraviolet ray of 365 nm wavelength) through a photomask(having a pattern with 500 μm squares dots) by use of an ultrahighpressure mercury lamp. The dose was 100 mJ/cm².

[0457] After the completion of the photoexposure, the photoexposeddielectric layer was treated by a shower development for 2 minutes withan aqueous solution of 0.12% by mass of tetramethylammonium hydroxide(25° C.) as the developer. Thereafter the dielectric layer was washedwith ultrapure water to remove the area that had been solubilized byultraviolet irradiation. Thus, a pattern was formed.

[0458] (4) Curing of Dielectric Pattern

[0459] The patterned dielectric layer on the printed wiring board wascured in an oven at 200° C. for 60 minutes to form a dielectric patternon the printed wiring board.

[0460] The patterning properties and dielectric properties of theobtained dielectric pattern were measured by the above methods. Theresults are shown in Table 3.

Example 7

[0461] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 3 in the same manner as inExample 6. A photosensitive dielectric layer was formed in a thicknessof 7 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 6 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 3.

Example 8

[0462] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 3 in the same manner as inExample 6. A photosensitive dielectric layer was formed in a thicknessof 5 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 6 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 3.

Example 9

[0463] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 3 in the same manner as inExample 6. In this embodiment, the NMP solution of polyimide prepared inSynthesis Example 3 (solid content:solvent=20:80 (by weight)) was usedas the alkali developable resin (B) and the solvent (D). Aphotosensitive dielectric layer was formed in a thickness of 3 μm andthereafter photoexposed, developed and cured in the same manner as inExample 6 to form a dielectric pattern, except that the above-preparedcomposition was used and the curing was carried out at 230° C. Theresultant dielectric pattern was subjected to the measurements of thepatterning properties and dielectric properties. The results are shownin Table 3.

Example 10

[0464] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 3 in the same manner as inExample 6. A photosensitive dielectric layer was formed in a thicknessof 3 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 6 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 3.

Comparative Example 6

[0465] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 3 in the same manner as inExample 6. A photosensitive dielectric layer was formed in a thicknessof 3 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 6 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 3. TABLE 3 Ex. 6Ex. 7 Ex. 8 Ex. 9 Ex. 10 Comp. Ex. 6 Photosensitive composition forforming dielectric Component Type Parts Type Parts Type Parts Type PartsType Parts Type Parts (A-I) Inorganic superfine A-5 15 A-5 15 A-3 10 A-3 10 A-5 10 — particles Material Titania Titania Barium Barium Titaniatitanate titanate Ave. particle diameter (μm) 0.02 0.02 0.03 0.03 0.02(A-II) Inorganic superfine A-1 85 A-1 85 A-1 90 A-4  90 A-4 90 A-2 100particles Material Barium Barium Barium Barium Barium Barium titanatetitanate titanate titanate titanate titanate Ave. particle diameter (μm)0.1 0.1 0.1 0.1 0.1 0.2 (B) Alkali developable resin Copolymer CopolymerCopolymer Polyimide Copolymer Copolymer (I) (II) (I) (I) (I)Weight-average molecular 50,000 100,000 50,000 80,000 50,000 50,000weight (Mw) Parts by weight 30 25 30 30 30 30 (C5) Photoacid generatorC5-1  2 C5-1  2 C5-1  2 C5-1  2 C5-1  2 C5-1  2 (D) Solvent D-1 50 D-150 D-1 50 NMP 120 D-1 50 D-1 50 D-3 50 D-3 50 D-3 50 D-3 50 D-3  50Patterning properties Patterning accuracy AA AA AA AA AA AA Patterndeletion AA AA AA AA AA AA Characteristics of dielectric Thickness (μm)7 7 5 3 3 7 Dielectric constant 23 25 30 28 25 15 Dielectric losstangent 0.05 0.04 0.05 0.04 0.04 0.03 Moist heat resistance AA AA AA AAAA AA Leakage current (A/cm²) 10⁻¹¹ 10⁻¹¹ 10⁻¹¹ 10⁻¹¹ 10⁻¹¹ 10⁻⁹

Example 11

[0466] (1) Preparation of Photosensitive Composition for FormingDielectric

[0467] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 3 in the same manner as inExample 6.

[0468] (2) Preparation of Photosensitive Transfer Film

[0469] The above-obtained composition was applied onto a copper foilsubstrate film (300 mm wide, 500 mm long and 13 μm thick) with a diecoater. The applied composition was dried at 100° C. for 5 minutes toremove the solvent. As a consequence, a photosensitive transfer layerfor forming a dielectric was formed in a thickness of 10 μm on thesubstrate film to prepare a photosensitive transfer film.

[0470] (3) Transferring of Photosensitive Transfer Layer

[0471] The photosensitive transfer film was superposed on a printedwiring board so that the photosensitive transfer layer would be incontact with the printed wiring board. Thereafter, the photosensitivetransfer film was thermocompression bonded with the board by use of aheating roller. The thermocompression bonding conditions were such thatthe heating roller had a surface temperature of 120° C., a rollingpressure of 4 kg/cm², and a traveling speed of 0.5 m/min. As a result,the copper-foiled photosensitive layer for forming a dielectric wastransferred on the printed wiring board to obtain a board with thephotosensitive dielectric layer. The thickness of the photosensitivedielectric layer was measured to be 10±1 μm.

[0472] (4) Photoexposure and Development of Dielectric Layer

[0473] A positive DFR was laminated on the above-formed multilayeredboard. The resultant laminate was irradiated through a photomask (havinga pattern with 500 μm squares dots) with i-line radiation (ultravioletray of 365 nm wavelength) by use of an ultrahigh high pressure mercurylamp. The photoexposed DFR layer was then developed by the conventionalmethod. Uncoated areas of the copper foil given by the development werechemically etched with a cupric chloride solution to form aphotosensitive dielectric layer with a patterned copper foil. Whileusing the copper foil pattern as a photomask, the photosensitivedielectric layer was photoexposed with an ultrahigh pressure mercurylamp. The dose was 400 mJ/cm².

[0474] After the completion of the photoexposure, the exposed dielectriclayer was treated by a shower development for 2 minutes with an aqueoussolution of 0.12% by mass of tetramethylammonium hydroxide (30° C.) asthe developer. Thereafter the dielectric layer was washed with ultrapurewater to remove the area that had been solubilized by ultravioletirradiation. Thus, a pattern was formed.

[0475] (5) Curing of Dielectric Pattern

[0476] The patterned dielectric layer with the copper foil on theprinted wiring board was cured in an oven at 200° C. for 30 minutes toform a dielectric pattern with the copper foil on the printed wiringboard.

[0477] The patterning properties and dielectric properties of theobtained dielectric pattern were measured by the above methods. Theresults are shown in Table 4.

Example 12

[0478] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 4 in the same manner as inExample 6. A photosensitive dielectric layer was formed in a thicknessof 10 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 11 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 4.

Example 13

[0479] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 4 in the same manner as inExample 6. In this embodiment, the NMP solution of polyimide prepared inSynthesis Example 3 (solid content:solvent=20:80 (by weight)) was usedas the alkali developable resin (B) and the solvent (D). Aphotosensitive dielectric layer was formed in a thickness of 10 μm andthereafter photoexposed, developed and cured in the same manner as inExample 11 to form a dielectric pattern, except that the above-preparedcomposition was used and the curing was carried out at 230° C. Theresultant dielectric pattern was subjected to the measurements of thepatterning properties and dielectric properties. The results are shownin Table 4.

Comparative Example 7

[0480] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 4 in the same manner as inExample 6. A photosensitive dielectric layer was formed in a thicknessof 10 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 11 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 4. TABLE 4 Ex. 11Ex. 12 Ex. 13 Comp. Ex. 7 Photosensitive composition for formingdielectric Component Type Parts Type Parts Type Parts Type Parts (A-I)Inorganic superfine particles A-5 15 A-3 10 A-3  10 — Material TitaniaBarium Barium titanate titanate Average particle diameter. (μm) 0.020.03 0.03 (A-II) Inorganic superfine particles A-1 85 A-1 90 A-4  90 A-2100 Material Barium Barium Barium Barium titanate titanate titanatetitanate Average particle diameter (μm) 0.1 0.1 0.1 0.2 (B) Alkalidevelopable resin Copolymer (I) Copolymer (I) Polyimide Copolymer (I)Weight-average molecular weight (Mw) 50,000 50,000 80,000 50,000 Partsby weight 35 35 40 35 (C5) Photoacid generator C5-1  2 C5-1  2 C5-1  2C5-1  2 (D) Solvent D-1 75 D-1 75 NMP 160 D-1  75 D-3 75 D-3 75 D-3  75Patterning properties Patterning accuracy AA AA AA AA Pattern deletionAA AA AA AA Characteristics of dielectric Thickness (μm) 10 10 10 10Dielectric constant 20 20 20 13 Dielectric loss tangent 0.04 0.04 0.040.03 Moist heat resistance AA AA AA AA Leakage current (A/cm²) 10⁻¹²10⁻¹² 10⁻¹² 10⁻¹²

[0481] <Third Photosensitive Composition For Forming Dielectric>

[0482] The following is a list of the components used in Examples 14-17and Reference Examples 1-2.

[0483] Inorganic Particles (A):

[0484] A-1: barium titanate particles (trade name: BT-01 available fromSakai Chemicals Co., Ltd., mean particle diameter: 0.1 μm, dielectricconstant: 500)

[0485] A-3: barium titanate nanoparticles (Nisshin Engineering Inc.,mean particle diameter: 0.03 μm, dielectric constant: 400)

[0486] A-4: barium titanate particles (TOHO TITANIUM CO., LTD., meanparticle diameter: 0.1 μm, dielectric constant: 400)

[0487] A-5: titania nanoparticles (trade name: RTIPBC available fromC.I. KASEI CO., LTD., mean particle diameter: 0.02 μm, dielectricconstant: 100)

[0488] Alkali Soluble Resin (B2):

[0489] B2-1: copolymer prepared from n-butyl methacrylate,3-hydroxypropyl methacrylate and methacrylic acid in 60/20/20 ratio (%by mass) (Mw: 50,000)

[0490] B2-2: copolymer prepared from n-butyl methacrylate,3-hydroxypropyl methacrylate and methacrylic acid in 60/20/20 ratio (%by mass) (Mw: 100,000)

[0491] Compound Having Ethylenically Unsaturated Group (C6):

[0492] C6-1: trimethylolpropane triacrylate

[0493] Photopolymerization Initiator (C7):

[0494] C7-1: 2-benzyl-2-dimethylamino-1-(4-morpholinophenyl)butane-1-one

[0495] Solvent (D):

[0496] D-3: propylene glycol monomethyl ether

[0497] Dispersant (E1):

[0498] E1-1: oleic acid

[0499] Filler (E2):

[0500] E2-1: acetylene black

Examples 14

[0501] (1) Preparation of Photosensitive Composition for FormingDielectric

[0502] The inorganic superfine particles (A-I), inorganic fine particles(A-II), alkali soluble resin (B2), compound having an ethylenicallyunsaturated group (C6), photopolymerization initiator (C7), solvent (D),dispersant (E) and filler (F) in the mixing ratio listed in Table 5,were kneaded together in a bead mill. Then, the mixture was filteredthrough a stainless steel mesh (500 mesh) to yield a photosensitivecomposition for forming a dielectric.

[0503] (2) Application of Photosensitive Composition for FormingDielectric

[0504] The above photosensitive composition was applied by a spinneronto a printed wiring board. The applied composition was dried at 100°C. for 5 minutes to remove the solvent. As a result, a photosensitivedielectric layer was formed in a thickness of 7 μm.

[0505] (3) Photoexposure and Development of Dielectric Layer

[0506] The photosensitive dielectric layer was irradiated with i-lineradiation (ultraviolet ray of 365 nm wavelength) through a photomask(having a pattern with 500 μm squares dots) by use of a ultrahighpressure mercury lamp. The dose was 400 mJ/cm².

[0507] After the completion of the photoexposure, the photoexposeddielectric layer was treated by a shower development for 1 minute withan aqueous solution of 0.5% by mass of sodium carbonate (30° C.) as thedeveloper. Thereafter the dielectric layer was washed with ultrapurewater to remove the uncured area, which had not been exposed toultraviolet irradiation. Thus, a pattern was formed.

[0508] (4) Curing of Dielectric Pattern

[0509] The patterned dielectric layer on the printed wiring board wascured in an oven at 200° C. for 30 minutes to form a dielectric patternon the printed wiring board.

[0510] The patterning properties and dielectric properties of theobtained dielectric pattern were measured by the above methods. Theresults are shown in Table 5.

Example 15

[0511] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 5 in the same manner as inExample 14. A photosensitive dielectric layer was formed in a thicknessof 7 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 14 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 4.

Example 16

[0512] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 5 in the same manner as inExample 14. A photosensitive dielectric layer was formed in a thicknessof 5 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 14 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 4.

Example 17

[0513] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 5 in the same manner as inExample 14. A photosensitive dielectric layer was formed in a thicknessof 3 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 14 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 4.

Reference Example 1

[0514] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 5 in the same manner as inExample 14. A photosensitive dielectric layer was formed in a thicknessof 7 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 14 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 4.

Reference Example 2

[0515] A photosensitive composition for forming a dielectric wasprepared in the mixing ratio listed in Table 5 in the same manner as inExample 14. A photosensitive dielectric layer was formed in a thicknessof 5 μm and thereafter photoexposed, developed and cured in the samemanner as in Example 14 to form a dielectric pattern, except for the useof the above-prepared composition. The resultant dielectric pattern wassubjected to the measurements of the patterning properties anddielectric properties. The results are shown in Table 4. TABLE 5 Ex. 14Ex. 15 Ex. 16 Ex. 17 Ref. Ex. 1 Ref. Ex. 2 Photosensitive compositionfor forming dielectric Component Type Parts Type Parts Type Parts TypeParts Type Parts Type Parts (A-I) Inorganic superfine A-5 15 A-5 15 A-310 A-3 10 A-5 15 A-5 15 particles Material Titania Titania Barium BariumTitania Titania titanate titanate Ave. particle diameter (μm) 0.02 0.020.03 0.03 0.02 0.02 (A-II) Inorganic superfine A-1 85 A-1 85 A-1 90 A-490 A-1 85 A-1 85 particles Material Barium Barium Barium Barium BariumBarium titanate titanate titanate titanate titanate titanate Ave.particle diameter (μm) 0.1 0.1 0.1 0.1 0.1 0.1 (B2) Alkali soluble resinB2-1 B2-2 B2-1 B2-1 B2-1 B2-1 Weight-average molecular 50,000 100,00050,000 50,000 50,000 50,000 weight (Mw) Parts by weight 20 20 20 20 2020 (C6) Ethylenically unsaturated C6-1 10 C6-1 10 C6-1 10 C6-1 10 C6-1 1C6-1 50 group-containing compound (C7) Photopolymerization C7-1 1 C7-1 1C7-1 1 C7-1 1 C7-1 1 C7-1 1 initiator (D) Solvent D-3 100 D-3 100 D-3100 D-3 100 D-3 100 D-3 100 (E1) Dispersant E1-1 1 E1-1 1 E1-1 1 E1-1 1E1-1 1 E1-1 1 (E2) Filler E2-1 0.5 E2-1 0.5 E2-1 0.5 E2-1 0.5 E2-1 0.5E2-1 0.5 Patterning properties Patterning accuracy AA AA AA AA BB BBPattern deletion AA AA AA AA BB AA Characteristics of dielectricThickness (μm) 7 7 5 3 7 5 Dielectric constant 20 22 30 28 25 18Dielectric loss tangent 0.05 0.04 0.04 0.04 0.2 0.05 Moist heatresistance AA AA AA AA BB AA Leakage current (A/cm²) 10⁻¹¹ 10⁻¹¹ 10⁻¹¹10⁻¹¹ 10⁻⁸ 10⁻¹¹

What is claimed is:
 1. A photosensitive composition for forming adielectric comprising (A) inorganic particles, (B) an alkali developableresin, and (C) additives, wherein: the alkali developable resin (B)comprises an alkali soluble resin having a phenolic hydroxyl group (B1);and the additives (C) comprise a compound having a quinonediazido group(C1), a compound containing at least two alkyletherified amino groups inthe molecule (C2) and a thermal acid generator (C3).
 2. A photosensitivecomposition for forming a dielectric comprising (A) inorganic particles,(B) an alkali developable resin, and (C) additives, wherein: the alkalidevelopable resin (B) comprises an alkali soluble resin having aphenolic hydroxyl group (B1); and the additives (C) comprise a compoundhaving a quinonediazido group (C1), a compound containing at least twoalkyletherified amino groups in the molecule (C2), a thermal acidgenerator (C3) and crosslinked fine particles (C4).
 3. Thephotosensitive composition for forming a dielectric as claimed in claim2, wherein the crosslinked fine particles (C4) have a mean particlediameter of 30 to 500 nm.
 4. A photosensitive composition for forming adielectric comprising (A) inorganic particles, (B) an alkali developableresin, and (C) an additive, wherein: the inorganic particles (A)comprise inorganic superfine particles (A-I) having a mean particlediameter of less than 0.05 μm and inorganic fine particles (A-II) havinga mean particle diameter of not less than 0.05 μm; and the additive (C)comprises a photoacid generator (C5).
 5. The photosensitive compositionfor forming a dielectric as claimed in claim 4, wherein the inorganicsuperfine particles (A-I) are contained at 1 to 30 parts by mass and theinorganic fine particles (A-II) are contained at 99 to 70 parts by masson the basis of 100 parts by mass of the inorganic particles (A).
 6. Thephotosensitive composition for forming a dielectric as claimed in claim4, wherein the inorganic particles (A) are contained at 20 to 95% bymass, the alkali developable resin (B) is contained at 1 to 60% by massand the photoacid generator (C5) is contained at 0.1 to 30% by mass. 7.The photosensitive composition for forming a dielectric as claimed inany one of claims 4 to 6, which is capable of forming a dielectric byheating at 500° C. or below, said dielectric having a dielectricconstant of not less than 20 and a dielectric loss tangent of not morethan 0.1.
 8. The photosensitive composition for forming a dielectric asclaimed in any one of claims 4 to 7, wherein the inorganic particles (A)comprise a titanium-containing metal oxide.
 9. The photosensitivecomposition for forming a dielectric as claimed in any one of claims 4to 8, wherein the alkali developable resin (B) is at least one resinselected from the group consisting of a (meth)acrylic resin, ahydroxystyrene resin, a novolak resin, a polyester resin, a polyimideresin, a nylon resin and a polyetherimide resin.
 10. A photosensitivecomposition for forming a dielectric comprising (A) inorganic particles,(B) an alkali developable resin, and (C) additives, wherein: theinorganic particles (A) comprise inorganic superfine particles (A-I)having a mean particle diameter of less than 0.05 μm and inorganic fineparticles (A-II) having a mean particle diameter of not less than 0.05μm; the alkali developable resin (B) comprises an alkali soluble resin(B2); and the additives (C) comprise a compound having an ethylenicallyunsaturated group (C6) and a photopolymerization initiator (C7).
 11. Thephotosensitive composition for forming a dielectric as claimed in claim10, wherein the inorganic superfine particles (A-I) are contained at 1to 30 parts by mass and the inorganic fine particles (A-II) arecontained at 99 to 70 parts by mass on the basis of 100 parts by mass ofthe inorganic particles (A).
 12. The photosensitive composition forforming a dielectric as claimed in claim 10, wherein the inorganicparticles (A) are contained at 20 to 95% by mass, the alkali solubleresin (B2) is contained at 1 to 60% by mass, the compound having anethylenically unsaturated group (C6) is contained at 0.1 to 30% by massand the photopolymerization initiator (C7) is contained at 0.1 to 20% bymass.
 13. The photosensitive composition for forming a dielectric asclaimed in any one of claims 10 to 12, which is capable of forming adielectric by heating at 500° C. or below, said dielectric having adielectric constant of not less than 20 and a dielectric loss tangent ofnot more than 0.1.
 14. The photosensitive composition for forming adielectric as claimed in any one of claims 10 to 13, wherein theinorganic particles (A) comprise a titanium-containing metal oxide. 15.The photosensitive composition for forming a dielectric as claimed inany one of claims 10 to 14, wherein the alkali soluble resin (B2) is aresin selected from the group consisting of a (meth)acrylic resin, ahydroxystyrene resin, a novolak resin and a polyester resin.
 16. Thephotosensitive composition for forming a dielectric as claimed in anyone of claims 10 to 15, wherein the compound having an ethylenicallyunsaturated group (C6) is a (meth)acrylate compound.
 17. Thephotosensitive composition for forming a dielectric as claimed in anyone of claims 10 to 16, wherein the compound having an ethylenicallyunsaturated group (C6) is contained at 20 to 500 parts by mass based on100 parts by mass of the alkali soluble resin (B2).
 18. A photosensitivetransfer film comprising a substrate film and a layer of aphotosensitive composition for forming a dielectric comprising inorganicparticles (A), an alkali developable resin (B) and an additive (C), saidlayer being provided in a thickness of 1 to 100 μm on the substratefilm, wherein: the inorganic particles (A) comprise inorganic superfineparticles (A-I) having a mean particle diameter of less than 0.05 μm andinorganic fine particles (A-II) having a mean particle diameter of notless than 0.05 μm; and the additive (C) comprises a photoacid generator(C5).
 19. The photosensitive transfer film as claimed in claim 18, whichis capable of forming a dielectric by heating at 500° C. or below, saiddielectric having a dielectric constant of not less than 20 and adielectric loss tangent of not more than 0.1.
 20. The photosensitivetransfer film as claimed in claim 18 or 19, wherein the inorganicparticles (A) comprise a titanium-containing metal oxide.
 21. Thephotosensitive transfer film as claimed in any one of claims 18 to 20,wherein the alkali developable resin (B) is a resin selected from thegroup consisting of a (meth)acrylic resin, a hydroxystyrene resin, anovolak resin, a polyester resin, a polyimide resin, a nylon resin and apolyetherimide resin.
 22. A dielectric prepared from the photosensitivecompositions for forming a dielectric as claimed in any one of claims 1to
 17. 23. A dielectric prepared by heating the photosensitivecompositions for forming a dielectric as claimed in any one of claims 4to 17 at 500° C. or below to cure the same, said dielectric having adielectric constant of not less than 20 and a dielectric loss tangent ofnot more than 0.1.
 24. A dielectric formed with use of thephotosensitive transfer film as claimed in any one of claims 18 to 21.25. A dielectric with a conductive foil, in which a dielectric obtainedfrom the photosensitive composition for forming a dielectric as claimedin any one of claims 4 to 9 or from the photosensitive transfer film asclaimed in any one of claims 18 to 21 is formed on the conductive foil.26. An electronic part including the dielectric as claimed in any one ofclaims 22 to 25.